JPS607259B2 - Silver halide photographic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an X-ray photographic image and a silver halide photographic material for X-rays used therein.

In X-ray photography using silver halide photographic materials, various techniques are employed for the purpose of reducing the radiation dose to patients, photographers, operators, etc.
These technologies are indispensable not only for reducing individual exposure doses, but also for reducing the chances of collective radiation exposure.

Recently, with the increase in the number of medical X-ray examinations in particular, reductions in exposure doses have been strongly demanded not only by the medical community but also by international public opinion. To meet this demand, devices and instruments such as intensifying screens, light plates, and X-ray photomultiplier tubes are used, but improvements in these devices and instruments in recent years and the sensitivity of X-ray photographic materials have been made in recent years. The rise has been remarkable.

On the other hand, with recent advances in medical X-ray examination technology, X-ray imaging technology that irradiates large doses of radiation is required in order to perform more accurate examinations, and for this purpose large-capacity X-ray generators have also been developed. There is.

However, as mentioned above, such an imaging technique that requires a large amount of radiation is not desirable because it goes against the desire to reduce the exposure dose. For this reason, there is a strong demand for the development of photosensitive materials with even higher sensitivity or intensifying screens with higher intensification factors. The first object of the present invention is to provide a novel method for forming radiographic images without radiography to meet this demand.

Another object of the present invention is to provide a novel x-ray-free silver halide photographic material for use in the above-mentioned image forming method.

The inventor of the present invention continued extensive exploration and research into an X-ray photography system for achieving the above object, and as a result, discovered that the method of the present invention is extremely superior.

That is, (i) a silver halide photographic material containing at least one selected from the following compounds {1} and {2-; (ii) a rare earth activated with terbium (Tb) as a crab photosensitizing screen; compounds, especially those of general formula [1
]X202S:Tb (where X is lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd)
), promethium (Pm), samarium (Sm), europium (Eu), doryium (Ga), terbium (Tb), dysprosium (Dy), holmium (Ho
), erbium (Er), thulium (Tu), ytterbium (Yd), lutetium (Lu), scandium (
Sc) and yttrium (Y).

The above object has been achieved in an image forming method characterized in that a crab photosensitizing screen containing a rare oxysulfide shown in ] as a crab photo component is combined, irradiated with X-rays, and developed. In the present invention, "X-ray irradiation" means irradiation with high-energy electromagnetic waves, and specifically means irradiation with X-rays and y-rays. [11] It is already well known that a crab light intensifying screen is used in X-ray photography, particularly in direct medical X-ray photography.

Calcium tungstate (CaW04) has traditionally been used as the crab light component used in this crab light intensifying screen, but this compound does not have sufficient emission intensity and its emission spectrum is on the short wavelength side even in the visible range. Therefore, silver halide photographic materials used in photography have been used that contain relatively large grains of silver halide and are sensitive to short wavelength light.

However, when photographing using a combination of this crab light intensifying screen and photosensitive material, it is possible to not only reduce the exposure dose but also to
It is also extremely difficult to require high image quality for the obtained X-ray images. In addition, attempts have been made to sensitize using dyes that are commonly used in general photographic materials, but this is not expected to be sufficiently effective for the purpose of moderately reducing radiation exposure. cannot be expected, and is at most half of the current level.
The reality is that there is a limit to the degree of exposure, and moreover, it is considered difficult to obtain X-ray photographs of even higher quality than at present. Therefore, in recent years, the system from the X-ray generator to the processing has been reviewed, and research has been carried out on crab photosensitizing screens and photosensitive materials that can be combined with them, especially from the perspective of reducing the exposure dose. It has been found that a rare earth compound activated with terbium, especially one containing an earth oxysulfide represented by the above general formula [1] as a crab light component, is useful as a crab light intensifying screen.

However, it is only known that it is desirable to use photosensitive materials that are color-sensitized to longer wavelengths than before, and a material that is completely compatible with this intensifying screen has not been found so far. The reality is that

This is simply because when using an emulsion sensitized to longer wavelengths than the conventional emulsion, sufficient sensitivity cannot be obtained.
〇〇Some products have undesirable performance, such as not having sufficient shelf life and becoming desensitized over time, color stains remaining after rapid processing, and fogging caused by exposure to the conventionally used safelight. This is because there are many. Another object of the present invention is to provide a silver halide photographic light-sensitive material for X-rays that is free from the above-mentioned drawbacks and is fully compatible with full-length photosensitive screens containing rare earth compounds.

Another object of the present invention is to provide a spectrally sensitized halogen synthetic fiber photographic emulsion for X-rays, which is suitable for a fin photosensitizing screen and contains a rare compound represented by the general formula [1] as a light component. It's about doing.

Yet another object of the present invention is to provide a method for obtaining high-sensitivity, high-quality radiographic images without making any changes to the current radiographic processing system.

Still another object of the present invention is to provide a silver halide photographic material for X-rays that has excellent graininess and high covering power.

According to one preferred embodiment of the present invention, the sensitivity of the photosensitive material can be increased several times that of current products without impairing image quality such as graininess and sharpness. In other words, the amount of X-ray exposure during imaging can be reduced to a fraction of the current amount. Further, according to another embodiment of the present invention, it is possible to obtain an X-ray image with extremely high image quality without impairing the current sensitivity.

These dyes used in the present invention can be easily synthesized by known methods such as the method described in Tsubaki Publication No. 43-13821 or a method analogous thereto.

These sensitizing dyes can be added to silver halide photographic emulsions using water-miscible organic compounds such as lower alcohols (e.g. methanol, ethanol), halogenated alcohols (e.g. trichloroethyl alcohol, tetrachloropropyl alcohol), etc. It may be added after being dissolved in a solvent.

Further, these sensitizing dyes may be added to the silver halide photographic emulsion at any time during the emulsion manufacturing process, but it is generally preferable to add them immediately after the completion of the second ripening.

The amount added varies depending on the type of silver halide emulsion, but the total amount of dyes added per mole of silver halide can range from 10 parts to 9 parts, preferably 30 parts. It is desirable to use it in the range of 9 to 200.

Further, the dye used in the present invention can be added and contained in the emulsion alone to obtain the effect of the present invention, but if necessary, other sensitizing dyes may be added in combination within a range that does not impair the effect of the present invention. You can also do that.

Next, typical dyes that can be added in combination with the dye according to the present invention are illustrated. Pigment {i-pigment'.

}Dye within the dye〇Dye■ Dye N Dye RiverThe silver halide photographic light-sensitive material according to the present invention includes various elements used therein, such as the support and various constituent layers including the silver halide emulsion layer. Various additives, binders, etc. can be used.

For example, as a support, a film made of polyethylene terephthalate, polycarbonate, polystyrene, polypropylene, cellulose acetate, etc. can be used, and as a binder, gelatin, gelatin derivatives, colloidal albumin, agar, gum arabic, alginic acid, etc. can be used. Cellulose derivatives such as cellulose acetate hydrolyzed to an acetyl content of 19-26%, acrylamide, imidized polyacrylamide, zein, vinyl alcohol containing urethane carboxylic acid groups or cyanoacetyl groups such as vinyl alcohol vinyl cyanoacetate copolymers. Polymers such as polyvinyl alcohol, polyvinylpyrrolidone, hydrolyzed polyvinyl acetate, and polymers obtained by polymerizing white matter or saturated acylated proteins with monomers having vinyl groups can be used. Various silver halides such as silver bromide, silver chloride, silver chlorobromide, silver iodobromide, and silver iodochlorobromide are used in the silver halide emulsion. Sulfur sensitizers such as furylthiocarbamide, thiourea, allylisothiocyanate, cystine, active or inactive selenium sensitizers, such as potassium chloroaurate, auricul trichloride, potassium auricular thiocyanate, 2-aurothiae. Gold compounds such as benzothiazole methyl chloride, palladium compounds such as ammonium chloroparadate and sodium chloropalladite, platinum compounds such as potassium chloroplatinate, noble metal compounds such as ruthenium compounds, rhodium compounds, iridium compounds, etc. Sensitization can be achieved using a sensitizer or a combination of such sensitizers. In addition to chemical sensitization, this emulsion can be reduced sensitized with a reducing agent, and can be further sensitized with triazoles, imidazoles, azaindenes, benzothiazolium compounds, zinc compounds, cadmium compounds, mercaptans, and mixtures thereof. The emulsion can be stabilized with sensitizing compounds of the thioether type, quaternary ammonium salt type or polyaltylene oxide type.The emulsion can also be stabilized with sensitizing compounds of the thioether type, quaternary ammonium salt type or polyaltylene oxide type. Wetting agents, plasticizers, film property improvers, etc., dihydroalkanes such as ethylene bisglycolic acid esters, bisethoxyethylene glycol succinate, water-dispersible fine particulate polymer compounds obtained by emulsion polymerization, etc. It can contain ethyleneimine compounds, dioxane derivatives, oxypolysaccharides, dicarboxylic acid chlorides, hardeners such as biesters of methanesulfonic acid, and is used as a coating aid for saponiso, sulfosuccinates, etc. It can contain various photographic additives such as activators and anti-stain agents.
The materials described in each of the publications No. 324 and No. 50-91315 can be effectively used. Furthermore, the photosensitive material according to the present invention can be developed in the same manner as ordinary X-ray photosensitive materials. In addition, layers other than the silver halide emulsion layer can contain the various photographic additives mentioned above, and the same binders can be used as binders. A cross-over effect prevention layer containing various dyes can also be provided. Next, the present invention will be illustrated by examples, but the embodiments of the present invention are not limited thereto.

In the following examples, the following dyes were used for comparison.

Comparative dye A Comparative dye B Comparative dye C Comparative dye D Comparative dye E Comparative dye F Comparative dye G Comparative dye Day Comparative dye I Example 1 98 mol percent silver bromide and 2 mol percent silver iodide prepared by a conventional method A highly sensitive silver iodobromide emulsion for X-rays was subjected to second back ripening using a gold sensitizer and a sulfur sensitizer, and then the emulsion was divided into equal parts and each part was sensitized as shown in Table 1. Added dye.

Next, after adding a stabilizer, a hardening agent, and a coating aid, the film was coated on both sides of the polyethylene terephthalate film base so that the dry film layer on one side was approximately 10 μm thick, and dried to form an X-ray photosensitive material. Created. This photosensitive material was passed through an optical converter and sandwiched between two crab light intensifying screens, and was irradiated with X-rays under the following two conditions.

(X-ray irradiation conditions) Also, as a light-receiving intensifying screen, G according to Kawamoto's invention is also 02S:
Two types of intensifying screens were used: one with Tb as the light component and an intensifying screen (DMS manufactured by Toshiba) with calcium tungstate (CaW04) as the light component.

These samples were then subjected to a sand treatment of 35q0,3 with a developer for X-ray photosensitive materials having the composition shown below, fixed, washed with water, and then dried with hot air. (Developer) Anhydrous sodium sulfite 70 parts Hydroquinone 10 parts Sodium carbonate (monohydrate) 20 parts 1 - Phoenix 1.3
- Pyrazolone 0.35 ta Potassium hydroxide
5-methyl-benztriazole
0.05 Potassium bromide
Sensitivity values were determined from the point at which the developed sample showed a density of 1.0 above fog.

The results are shown in Table 1. (Relative sensitivities are shown with the sensitivity of the sample obtained by combining the blank sample and DMS under the conditions 1 and 2 above as 100.)
1 As is clear from Table 1, when the photosensitive material containing the sensitizing dye according to the present invention is combined with a saddle photosensitive screen containing terbium-activated rare earth oxysulfide as a light component, , a light-sensitive material that is not color sensitized, and a crab light-sensitizing screen (DMS) containing calcium tungstate as a light component.
and a combination with a crab photosensitizing screen according to the present invention, a combination of a light-sensitive material color-sensitized with a dye other than the present invention--DMS and an intensifying screen according to the present invention, and a color sensitization with a dye according to the present invention. It has been found that, compared to the combination of the photosensitive material and DMS, an X-ray image with extremely high sensitivity can be obtained without an increase in capri or color contamination.

Example 2 A photosensitive material prepared in the same manner as in Example 1 was irradiated with X-rays under the conditions of a tube voltage of 100 kVp and a tube current of 100 A, and the granularity of the sample obtained by processing in the same manner as in Example 1 and freshness were determined by RMS and OTF.

RMS measurement is performed by placing an acrylic plate with a thickness of 10 mm in front of the photosensitive material sandwiched between intensifying screens, and under the above conditions for a time X such that the image density after processing becomes 1.0 on both sides. The emulsion layer on the front side was peeled off against the X-ray generator of the photosensitive material, and the emulsion layer on the other side was measured using a Sakura one-touch RMS measuring device (manufactured by Konishiroku Photo Industry Co., Ltd.). Measurements were made using an aperture size of 50 mm and a magnification of 5×1 fold.

To measure OTF, place an OTF measurement chart containing a square wave made from a ship with a skin thickness of 0.8 to 1011 ines closely on the back side of the front side of the intensifying screen, and place it on the back of the front side of the intensifying screen, which is shielded by the lead square wave on the film surface. X-rays are irradiated so that the density of the non-containing areas is 1.0 on both sides, and as in the case of RMS, one side of the emulsion is peeled off, and the square wave pattern on the other side is created using Sakura Microphone.

The measurement was performed using a densitometer model M-5 (manufactured by Konishiroku Photo Industry Co., Ltd.) by sweeping in a direction perpendicular to the rectangular wave. Note that the aperture size at this time is 2 in the parallel direction of the square wave.
30r, 25〆 in the right angle direction, and the magnification is 10M sound. The results are shown in Table 2 for RMS values, and OTF
The details are shown in Figure 1. *As is clear from Table 2 and Figure 1, the X-ray images obtained by the combination of the light-sensitive material of the present invention and the crab light intensifying screen are highly sensitive and compared to the current non-color sensitized light-sensitized screen. It was found that the granularity and freshness of the material were comparable to those of the combination of the material and the DMS intensifying screen. Example 3 Created on the same machine as Example 1, 100 kVp, 100 A, 0
．． A preservation test was conducted by leaving a sample subjected to X-ray irradiation and development using 068c at a high temperature.

The results are shown in Table 3. The intensifying screen used was one according to the present invention, and the sensitivity was expressed as a relative value with the sensitivity of a non-color sensitized sample immediately after coating as 100. A color-sensitized high-sensitivity silver iodobromide photosensitive material was left under safe light and tested for safety against Celite.

20W light source, Sakura No. Using a 4A safelight filter (manufactured by Konishi Roku4 Photo Industry Co., Ltd.), the photosensitive material was left at a distance of 100 cm from the light source for 1 hour, and then treated in the same manner as in Example 1 to eliminate fogging caused by the safelight and by visual inspection. The residual color after treatment was measured.

The results are shown in Table 4. The safelight property was expressed by the difference in density between each sample developed without safelight exposure. In addition, contamination was expressed on a five-point scale from 1 to 5, from least to least contamination. The photographic performance was measured using the intensifying screen according to the present invention, 100 kVp, 100 skin A, 0
．． Sample No. 06ec irradiation. This is the relative sensitivity when the sensitivity of 1 is set as 100.

As is clear from Table 4, it was found that the photosensitive materials using the dyes according to the present invention were free from color staining and had excellent safety against safelight.

[Brief explanation of the drawing]

FIG. 1 represents the OTF curve obtained in Example 2. Curve 1 was obtained from a combination of a sample (No. 4) outside the invention and DMS. Curve 2 is a sample of the present invention (No. 2) and DMS, and curve 3 is a sample of a sample other than the present invention (No. 2).
No. 4) and the intensifying screen according to the present invention, and curve 4 was obtained by a combination of the sample (No. 2) according to the present invention and the intensifying screen according to the present invention. Chrysanthemum diagram

Claims (1)

[Scope of Claims] 1. A fluorescent material containing a terbium-activated rare earth compound as a fluorescent component, characterized in that at least one compound selected from the following compounds (1) and (2) is added. A silver halide photographic material for X-rays that is used in combination with a photosensitizing screen. (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼