JPH0728201A - Radiograph forming method - Google Patents

Abstract

PURPOSE:To provide a radiograph forming method excellent in quality, especially in diagnosability with reduced exposure. CONSTITUTION:This radiograph forming method consisting of a silver halide sensitive material and an intensifying screen. In this case, (1) at least one of the screens exhibits >=25% absorption to the X-rays of 80KVp energy, and the contrast transmission function(CTF) is controlled to >=0.79 based on unit spatial frequency/mm, and (2) the silver halide photographic sensitive material has the same wavelength as the main emission peak wavelength of the screen stipulate in (1). The screen is exposed with a monochromatic light having 15+ or -5nm half-value width and developed with a developer at 35 deg.C for 25sec, the photosensitive layer on the opposite side of the exposed surface is released, then measurement is taken, and the screen has such a sensitivity that the exposure necessary to control the density obtained in the photosensitive layer to the minimum density plus 0.5 is <0.010lux sec.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an image forming method using a novel combination of a silver halide photographic light-sensitive material and a radiation intensifying screen.

[0002]

2. Description of the Related Art In medical radiography, attempts have been made to increase the sensitivity of a system in order to reduce the X-ray exposure amount of a patient, but there is no satisfactory system due to the problem of X-ray mottle. Radiographic intensifying screens range from those with high sharpness and low light emission to those with low sharpness and high light emission, and silver halide photographic materials having various combinations of sharpness and sensitivity are commercially available. However, a sufficiently satisfactory image forming method has not yet been found in this combination.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming method which has a good image quality (especially easy diagnosis) even when the exposure dose is reduced.

[0004]

The present invention is a method of forming a radiation image comprising a silver halide photographic light-sensitive material and a radiation intensifying screen, wherein (1) at least one of the radiation intensifying screens is , X-ray energy is 80 KVp
Shows an absorption amount of 25% or more for X-rays, and has a contrast transfer function (CTF) of 1 spatial frequency (1p) / mm
0.79 or more (preferably 3 spatial frequencies (1p) /
The radiation sensitizing screen has a wavelength of 0.36 mm or more), and (2) the silver halide photographic light-sensitive material has the same wavelength as the main emission peak wavelength of the radiation sensitizing screen defined in (1) above. And exposed with monochromatic light having a half-value width of 15 ± 5 nm, and using a developer [A] having the following composition, development was performed at a developer temperature of 35 ° C. and a development time of 25 seconds, and a photosensitive layer on the opposite side to the exposed surface was developed. After peeling, the density obtained in the photosensitive layer has a sensitivity such that the exposure amount required to reach a value obtained by adding 0.5 to the minimum density is less than 0.010 lux seconds. This is a characteristic image forming method. Composition of developer [A] Potassium hydroxide 21 g Potassium sulfite 63 g Boric acid 10 g Hydroquinone 25 g Triethylene glycol 20 g 5-Nitroindazole 0.2 g Glacial acetic acid 10 g 1-Phenyl-3-pyrazolidone 1.2 g 5-Methylbenzotriazole 0.055 g Glutaraldehyde 5 g Potassium bromide 4 g Water was added to make 1 liter, and the pH was adjusted to 10.02.

The silver halide photographic light-sensitive material preferably has at least one silver halide emulsion layer on each side of the support and has a crossover of 16% or more.
% Or less. More preferably 20 crossovers
% Or more and 30% or less. The sensitivity of the silver halide photographic light-sensitive material is 0.0020 lux seconds or more and 0.0090 or less, particularly 0.0020 or more and 0.
It is preferably less than 0045 lux seconds. As for the radiation intensifying screen, the description in Japanese Patent Application Nos. 4-193433 and 4-193432 can be referred to, and the screen can be prepared according to these descriptions. As a method for controlling the crossover of the silver halide photographic light-sensitive material within an appropriate range, a substance having absorption at the emission wavelength of the radiation intensifying screen (for example, a sensitizing dye, a base, a dye added to the light-sensitive layer, This can be done by controlling the absorption of the silver halide itself). As a method for controlling the sensitivity, many conventionally known methods are used.

The form of silver halide grains used in the present invention is preferably tabular grains having an aspect ratio of 2 or more. The silver halide that can be used in the silver halide emulsion may be any of silver bromide, silver iodobromide, silver iodochlorobromide, silver chlorobromide, silver chloride and the like. Preferred are silver iodobromide (1 = 0 to 10 mol%), silver bromide, and silver chlorobromide. A
The gI distribution may be internal high concentration or external high concentration, but external high concentration type is preferable. In the process of silver halide grain formation or physical ripening, a cadmium salt, a zinc salt, a lead salt, a thallium salt, an iridium salt or a complex salt thereof, a rhodium salt or a complex salt thereof, an iron salt or an iron complex salt may be present together. If necessary, chemical sensitization can be performed.

As the chemical sensitization method, a gold sensitization method using a so-called gold compound, a sensitization method using a metal such as iridium, platinum, rhodium or palladium, a sulfur sensitization method using a sulfur-containing compound, a tin salt, a polyamine or the like is used. Reduction sensitization, selenium compound sensitization, tellurium compound sensitization, or a combination of two or more of these can be used. When making a tabular silver halide emulsion,
Cugnac and Chateau "The Evolution of the Morphology of Physically Aged Silver Bromide Crystals (Evolution of the Morphology of Silver Bromide Crystals Dualing Physical Raising)" Science & Industry Photography 33, No. 2 (1962), p. 121-1
25, Duffin, "Photographic emulsion Chem
istry) "Focal Press, New York, 1966, p. 66-p. 72, APH Trivelli, WF Smith Photographic Journal, Volume 80, 2
Although it is described on page 85 (1940), etc.
-127,921, JP-A-58-113,927, JP-A-58-113,928, and the like, can be easily prepared. In addition, while forming a seed crystal in which tabular grains are present in an amount of 40% or more by weight in an atmosphere having a relatively low pBr value of pBr 1.3 or less, while simultaneously maintaining the same pBr value and adding a silver and halogen solution at the same time, Obtained by growing seed crystals. The silver amount of the light-sensitive material of the present invention is preferably 0.5 g / m ^{2 to} 5 g / m ² (on one side), more preferably 1 g / m ^{2 to} 3.4 g / m ² (on one side).

There are no particular restrictions on the various additives used in the light-sensitive material of the present invention. For example, JP-A-2-6853.
It is possible to use those described in the following relevant parts of Japanese Patent Publication No. 9: Item This section 1. Silver halide emulsion and its manufacturing method JP-A-2-68539, page 8, lower right column, line 6 from the bottom to page 10, upper right column, line 12 2. Chemical sensitization method, page 10, upper right column, line 13 to lower left column, line 16 3. Antifoggants / stabilizers, page 10, lower left column, line 17 to page 11, upper left column, line 7 and page 3, lower left column, line 2 to page 4, lower left column. 4. Spectral sensitizing dyes, page 4, lower right column, line 4 to page 8, lower right column. 5. Surfactants / antistatic agents, page 11, upper left column, line 14 to page 12, upper left column, line 9 6. Matting agents, slip agents, plasticizers, page 12, upper left column, line 10 to upper right column, line 10 Page 14, lower left column, line 10 to same, lower right column, line 1. 7. Hydrophilic colloid, page 12, upper right column, line 11 to left lower column, line 16 8. Hardener, page 12, lower left column, line 17 to page 13, upper right column, line 6 9. Support, page 13, upper right column, lines 7 to 20. Ten. Dyes / Mordants From page 13, left lower column, line 1 to page 14, left lower column, line 9

Regarding the developing solution, the fixing solution and the developing method used in the present invention, JP-A-2-103037, No. 16
Page 7, upper right column, line 7 to page 19, lower left column, line 15 and 2
The description from page 3, lower right column, line 5 to page 1-5, lower right column, line 10 of JP-A-115837 can be referred to.

[0010]

【Example】

[Example 1] (1) The following radiation intensifying screens were prepared in pairs (one for front and one for rear). HR-4 (commercially available from Fuji Photo Film Co., Ltd.) HR-12 (commercially available product from Fuji Photo Film Co., Ltd.) Trimax 12 (commercially available from 3M Company) Radiation intensifying screen A (prototype A) Radiation intensifying screen B (Prototype B)

1) Production of radiation intensifying screen A A phosphor (Gd ₂ O ₂ ) was used as a coating solution for forming a phosphor sheet.
S: Tb) 200 g, Binder A (Polyurethane, manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: Desmolac TPK
L-5-2625 [solid content 40%]) 20 g, and binder B (nitrocellulose, nitrification degree 11.5%) 2 g
Was added to a methyl ethyl ketone solvent and dispersed by a propeller mixer to prepare a coating liquid having a viscosity of 30 PS (25 ° C.) (binder / phosphor ratio = 1/20). This was coated on a polyethylene terephthalate (temporary support, thickness 180 μm) coated with a silicone-based release agent to give a film thickness of 160
It was applied so as to have a thickness of μm (film thickness after pressure compression treatment described later), dried, and then peeled from the temporary support to form a phosphor sheet. Separately, as an undercoat layer forming coating solution, 90 g of a soft acrylic resin and 50 g of nitrocellulose were added to methyl ethyl ketone and mixed and dispersed to have a viscosity of 3 to 6 PS (2
A dispersion liquid (5 ° C) was prepared.

Thickness of 250 μm in which titanium dioxide is kneaded
Polyethylene terephthalate (support) is placed horizontally on a glass plate, the above coating solution for forming the undercoat layer is uniformly applied on the support using a doctor blade, and then the temperature is gradually increased from 25 ° C to 100 ° C. And the coating film was dried to form an undercoat layer on the support (coating film thickness:
15 μm). Place the phosphor sheet prepared first on this, and use a calendar roll to 400 Kgw / cm ²
A pressure compression operation was performed at a pressure of 80 ° C.

Separately, a fluororesin (fluoroolefin / vinyl ether copolymer, manufactured by Asahi Glass Co., Ltd., trade name:
Lumiflon LF100) 70 g, crosslinking agent (isocyanate, Sumitomo Bayer Urethane Co., Ltd., trade name: Desmodur Z4370) 25 g, bisphenol A type epoxy resin 5 g, and alcohol-modified silicone oligomer (dimethyl polysiloxane skeleton, both ends Having a hydroxyl group (carbinol group) in the Shin-Etsu Chemical Co., Ltd.
Product name: X-22-2809 (5 g), product name, was added to a mixed solvent of toluene / isopropyl alcohol (1: 1, volume ratio) to prepare a coating liquid for forming a protective film. The above coating solution for forming a protective film is applied to the surface of the phosphor sheet that has been subjected to a pressure compression operation on a support using a doctor blade,
It was heat-treated at 120 ° C. for 30 minutes, dried and heat-cured to form a transparent protective film having a thickness of 3 μm. As described above, a radiation intensifying screen A composed of the support, the undercoat layer, the phosphor layer, and the transparent protective film was produced.

2) Production of the radiation intensifying screen B The above radiation intensifying screen A except that the phosphor sheet is formed so that the thickness of the phosphor sheet is 230 μm (the film thickness after pressure compression treatment). A radiation intensifying screen B composed of a support, an undercoat layer, a phosphor layer, and a transparent protective film was manufactured by repeating the manufacturing method of 1.

(2) Measurement of characteristics of radiographic intensifying screen 1) Measurement of X-ray absorption amount X-rays generated from a tungsten target tube operated at 80 KVp with three-phase power supply, and an aluminum plate having a thickness of 3 mm To reach the sample radiographic intensifying screen fixed at a position of 200 cm from the tungsten anode of the target tube, and then the amount of X-rays transmitted through the intensifying screen after 50 cm from the phosphor layer of the intensifying screen. Was measured using an ionization type dosimeter to determine the X-ray absorption amount. In addition, as a reference, the X-ray dose at the above-mentioned measurement position measured without passing through the intensifying screen was used. Table 1 shows the measured X-ray absorption of each intensifying screen.

2) Measurement of modulation transfer function (CTF) An MRE single-sided photosensitive material manufactured by Eastman Kodak Co. was placed in contact with an intensifying screen to be measured, and a rectangular chart for MTF measurement (made of molybdenum, thickness: 80 μm). , Spatial frequency: 0 lines / mm to 10 lines / mm) were photographed. The chart was raised at a position 2 m from the X-ray tube, the photosensitive material was placed in front of the X-ray source, and the intensifying screen was placed thereafter. The X-ray tube used is DRX-3724 manufactured by Toshiba Corporation.
It is HD, and uses a tungsten target, has a focal spot size of 0.6 mm × 0.6 mm, passes through an aluminum equivalent material of 3 mm including a diaphragm, and generates X-rays. A voltage of 80 KVp was applied to the three phases with a pulse generator, and an X-ray that passed through a filter of 7 cm of water having absorption almost equivalent to the human body was used as a light source. The light-sensitive material after photographing was prepared by using the developer [A] described above with a roller-conveying type automatic developing machine (FPM-5000) manufactured by Fuji Photo Film Co., Ltd.
C., and fixer F (ammonium thiosulfate (70% weight / volume) 200 ml, sodium sulfite 20 g, boric acid 8 g, ethylenediaminetetraacetic acid disodium salt (dihydrate))
Water was added to 0.1 g, 15 g of aluminum sulfate, 2 g of sulfuric acid, and 22 g of glacial acetic acid to make 1 liter, and then p
H was adjusted to 10.02) and the development treatment described above was performed at a temperature of 25 ° C. to prepare a measurement sample.
The exposure amount at the time of the above X-ray photography was adjusted so that the average value of the maximum density and the minimum density after the development processing would be 1.0.

Next, the measurement sample was operated with a microdensitometer. The operating direction of the aperture at this time is 30μ
The concentration profile was measured at a sampling interval of 30 μm using a slit of m, and a vertical direction of 500 μm. Repeat this operation 20 times to calculate the average value,
The concentration profile was used as the basis for calculating CTF.
After that, the peak of the rectangular wave for each frequency in this density profile was detected, and the density contrast for each frequency was calculated. Table 1 shows the values measured for one spatial frequency / mm.
Shown in.

3) Sensitivity measurement Using the same X-ray source as that used in the CTF measurement, a green-sensitized Eastman Kodak MRE single-sided photosensitive material was combined, and the X-ray exposure amount was measured by the distance method. , L
Step exposure was performed with a width of ogE = 0.15. After exposure, develop the photosensitive material under the same conditions as when measuring CTF,
A measurement sample was obtained. The density of the measurement sample was measured with visible light to obtain a characteristic curve. Sensitivity is expressed by the reciprocal of the X-ray exposure amount for obtaining a density of 1.0 at Dmin, and the intensifying screen for rear side arrangement HR-4 is used as a reference ("100"),
The relative sensitivity was investigated. The results are shown in Table 1.

Table 1 Intensifying screen X-ray absorption amount Sensitivity CTF (1 line / mm) HR-4 (front side) 22.3% 89 0.850 HR-4 (rear side) 23.1% 100 0.850 HR-12 (front side) 30.6% 181 0.773 HR-12 (rear side) 42.7% 275 0.681 Trimax12 (front side) 29.7% 151 0.782 Trimax12 (rear side) 47.3% 245 0.643 Intensifying screen A 32.8% 200 0.869 Intensifying screen B 43.2% 270 0.802

(3) The following silver halide photographic light-sensitive material was prepared. Super HRS (commercially available from Fuji Photo Film Co., Ltd.) Silver halide photographic light-sensitive material I Silver halide photographic light-sensitive material II

Preparation of Photosensitive Material I (Preparation of Emulsion A) 9 g of gelatin having an average molecular weight of 15,000 and 6 g of potassium bromide were added to 1 liter of water, and an aqueous silver nitrate solution was added to the aqueous solution kept at 55 ° C. with stirring. 37cc (Aqueous solution containing 4.00g of silver nitrate and 5.9g of potassium bromide 3
8 cc was added in 37 seconds by the double jet method. Next, after adding 18.6 g of gelatin, the temperature was raised to 70 ° C. and 89 cc of silver nitrate aqueous solution (silver nitrate 9.8 g) was added over 22 minutes. After adding 7 cc of 25% aqueous ammonia solution and physically aging for 10 minutes at the same temperature,
6.5 cc of 100 acetic acid aqueous solution was added. Subsequently, an aqueous solution of 153 g of silver nitrate and an aqueous solution of potassium bromide were added over 35 minutes by the control double jet method while maintaining the potential at pAg 8.5. The flow rate at this time was accelerated so that the flow rate at the end of addition was 10 times the flow rate at the start of addition. After addition is complete, 2N potassium thiocyanate solution 35
ml was added. After physically aging for 5 minutes at the same temperature, the temperature was lowered to 35 ° C. Thus, the average projected area diameter is 1.10 μm, the thickness is 0.16 μm, and the variation coefficient of diameter is 1
6.0% of monodisperse pure silver bromide tabular grains were obtained. After this, soluble salts were removed by the coagulation sedimentation method. The temperature was raised to 40 ° C again, and 35 g of gelatin and 2.35 of phenoxyethanol were added.
g, and 0.8 g of sodium polystyrene sulfonate as a thickener are added, and the pH is adjusted with caustic soda and silver nitrate solution.
It was adjusted to 6.10 and pAg 8.25. After raising the temperature to 56 ° C. and adding 0.4 g of ethylthiosulfonic acid,
Thiourea dioxide (0.043 mg) was added, and the mixture was held for 22 minutes for reduction sensitization. Then, 0.1 mol% of 0.08 μm AgI fine grain emulsion was added to and dissolved in silver. Next, 4-hydroxy-6-methyl-1,3,
20 mg of 3a, 7-tetrazaindene was added, and after 10 minutes, 500 mg of sensitizing dye-I and 2.5 mg of sensitizing dye-II were added. Furthermore, 0.83 g of an aqueous calcium chloride solution was added. After 10 minutes, 110 mg of potassium thiocyanate and 2.6 mg of chloroauric acid were added, and then selenium compound-I was added to 2.
4 mg and 1.6 mg of sodium thiosulfate were added, and the mixture was aged for 60 minutes. Thereafter, 35 mg of Compound-I was added, and then resin HP-21 manufactured by Mitsubishi Kasei was added and the mixture was stirred for 15 minutes to desorb the sensitizing dye, and then filtered using a filter to obtain Emulsion A.

[0022]

[Chemical 1]

(Preparation of Emulsion B) 7 g of gelatin having an average molecular weight of 15,000 and 6 g of potassium bromide were added to 1 liter of water, and 37 cc of an aqueous silver nitrate solution (silver nitrate 4. 00g) and potassium bromide 5.9g
38 cc of an aqueous solution containing C was added in 37 seconds by the double jet method. Next, after adding 18.6 g of gelatin,
The temperature is raised to 0 ° C and the aqueous solution of silver nitrate is 89cc (silver nitrate 9.8g).
Was added over 22 minutes. Here, 5 cc of 25% aqueous ammonia solution was added, and after physically aging for 10 minutes at the same temperature, 4.5 cc of 100 acetic acid aqueous solution was added. Subsequently, an aqueous solution of 153 g of silver nitrate and an aqueous solution of potassium bromide were added over 35 minutes by the control double jet method while maintaining the potential at pAg of 8.0. The flow rate at this time was accelerated so that the flow rate at the end of addition was 10 times the flow rate at the start of addition. After the addition was completed, 35 ml of 2N potassium thiocyanate solution was added. After physically aging for 5 minutes at the same temperature, the temperature was lowered to 35 ° C. Thus, monodisperse pure silver bromide tabular grains having an average projected area diameter of 0.85 μm, a thickness of 0.135 μm and a diameter variation coefficient of 18.5% were obtained.
After this, soluble salts were removed by the coagulation sedimentation method. The temperature was raised to 40 ° C again and 35 g of gelatin and 0.05 of proxel were added.
g, and 0.4 g of sodium polystyrene sulfonate as a thickener are added, and the pH is adjusted with caustic soda and silver nitrate solution.
It was adjusted to 5.80 and pAg 7.8. The temperature was raised to 54 ° C., 0.4 g of ethylthiosulfonic acid was added, and then 0.043 mg of thiourea dioxide was added, and the mixture was kept for 22 minutes for reduction sensitization. Next, 4-hydroxy-6
-Methyl-1,3,3a, 7-tetrazaindene 60 mg
Was added, and then, 0.1 mol% of 0.08 μm AgI fine grain emulsion with respect to silver was added and dissolved. After 10 minutes, 480 mg of Sensitizing Dye-I and 2.0 mg of Sensitizing Dye-II were added. Further, 0.4 g of sodium chloride aqueous solution was added. After 10 minutes, 30 mg of potassium thiocyanate and 2.0 mg of chloroauric acid were added, followed by 2.0 mg of selenium compound-I,
1.6 mg of sodium thiosulfate was added and the mixture was aged for 80 minutes. Thereafter, a sensitizing dye was desorbed in the same manner as in the emulsion A to obtain an emulsion B.

(Preparation of Coating Solution) <Preparation of Emulsion Coating Layer> Coating chemical A-1 was prepared by adding the following chemicals to chemically sensitized emulsion A per mol of silver halide. Sensitizing dye-I (added at 40 ° C. to give an interparticle dye adsorption distribution RDS = 18%) 250 mg. 2,6-bis (hydroxyamino) -4-diethylamino-1,3,5-triazine 72 mg. Trimethylol propane 9g Dextran (average molecular weight 39,000) 18.5g Potassium polystyrene sulfonate (average molecular weight 600,000) 1.8g Compound-I 1g Compound-II 4.8g Compound-III 1.5g -Compound-IV 200 mg-Compound-V 14 mg-Surfactant-I 3.2 g-Sodium polyacrylate (average molecular weight 40,000) 3.8 g-KI 83 mg-Snowtex C (Nissan Chemical Co., Ltd.) 29.1 g -Gelatin 70 g-NaOH pH was adjusted to 6.5. Hardener (1,2-bis (vinylsulfonylacetamide) ethane) The swelling ratio was adjusted to 200%.

[0025]

[Chemical 2]

[0026]

[Chemical 3]

Emulsion B chemically sensitized was added to silver halide 1
The following chemicals were added per mol to prepare a coating liquid B-1. -Sensitizing dye-I (same as A-1 but RDS = 17%) 240 mg-2,6-bis (hydroxyamino) -4-diethylamino-1,3,5-triazine 72 mg-trimethylolpropane 9 g-dextran ( Average molecular weight 39,000) 18.5 g-Potassium polystyrene sulfonate (average molecular weight 600,000) 1.8 g-Compound-I 3.4 g-Compound-II 4.8 g-Compound-III 1.5 g-Compound-V 42 mg sodium polyacrylate (average molecular weight: 40,000) 1.3 g - KI 83 mg, Snowtex C (Nissan chemical (Co.)) 29.1 g · gelatin 1m total coating amount of gelatin per ² is 2.6 g / m ² The amount added was adjusted accordingly. -Sulfuric acid The pH was adjusted to 5.9. Hardener (1,2-bis (vinylsulfonylacetamide) ethane) The swelling ratio was adjusted to 200%. Dye Emulsion A was added to the above coating solution so that the amount of Dye-I was 10 mg / m ² per side.

[0028]

[Chemical 4]

(1) Preparation of Dye Emulsion A 60 g of the above dye-I and the following high boiling point organic solvent-I
62.8 g, -II 62.8 g and ethyl acetate 333
g was melted at 60 ° C. Next, 65 cc of a 5% aqueous solution of sodium dodecylbenzenesulfonate, 94 g of gelatin and 581 cc of water were added, and the mixture was emulsified and dispersed by a dissolver at 60 ° C. for 30 minutes. Next, 2 g of the following compound-VI and 6 liters of water were added, and the temperature was lowered to 40 ° C. Next, using Asahi Kasei's ultrafiltration laboratory module ACP1050,
The mixture was concentrated to a total amount of 2 kg, and 1 g of the compound-VI was added to obtain a dye emulsion A.

[0030]

[Chemical 5]

<Preparation of Coating Solution for Surface Protective Layer> Coating solution C-1 was prepared so that the respective components had the following coating amounts. Gelatin 780 mg / m ² · Surfactant -I 45 mg / m ² · Surfactant -II 13 mg / m ² · Surfactant -III 6.5 mg / m ² · Surfactant -IV 3 mg / m ² · interface Activator-V 1 mg / m ² · Compound-III 2 mg / m ² · Compound-V 0.5 mg / m ² · Compound-VII 100 mg / m ² · Sodium polyacrylate (average molecular weight 80,000) 80 mg / m ² · Snowtex C (Nissan Chemical Co., Ltd.) 200 mg / m ² · Polymethylmethacrylate (average molecular weight 3.7 μm) 87 mg / m ² · Proxel (adjusted to pH 6.5 with NaOH) 0.5 mg / m ²

[0032]

[Chemical 6]

(2) Preparation of support Corona discharge treatment was performed on a biaxially stretched polyethylene terephthalate film having a thickness of 175 μm, and a first undercoat liquid having the following composition was applied at an amount of 4.9 cc / m ² . And a wire bar coater, and dried at 185 ° C. for 1 minute. Next, a first undercoat layer was similarly provided on the opposite surface. The polyethylene terephthalate used was one containing 0.04 wt% of Dye-I. * Butadiene-styrene copolymer latex solution (solid content 40% butadiene / styrene weight ratio = 31/69) 158cc * 2,4-dichloro-6-hydroxy-s-triazine sodium salt 4% solution 41cc * Distilled water 801cc * The latex solution contains the following compounds as an emulsifying dispersant in an amount of 0.4 wt% based on the latex solids.

[0034]

[Chemical 7]

A second undercoat layer having the following composition was applied on each of the above-mentioned first undercoat layers, one side at a time so that the coating amount was as described below, and 155 by a wire bar coater system on both sides. It was applied and dried at ℃.・ Gelatin 80 mg / m ²・ Coating aid-VI 1.8 mg / m ²・ Compound-VIII 0.27 mg / m ²・ Mat agent Polymethylmethacrylate 2.5 mg / m ^{2 with} an average particle size of 2.5 μm

[0036]

[Chemical 8]

(Preparation of photographic material) Emulsion layer B-1 and emulsion layer A on the support prepared as described above in order from the base.
-1, and the surface protection layer C-1 were combined, and three layers were coated on both sides by the simultaneous extrusion method to obtain a photographic material. The amount of coated silver per side is 1.0 g for the A-1 layer.
/ M ² , and the B-1 layer was 0.7 g / m ² .

Preparation of Sensitive Material II Same as in Sensitive Material I except that the sensitizing dye A-1 of the coating solution was added to 180
mg and B-1 sensitizing dyes were prepared as 160 mg.

Measurement of characteristics of silver halide photographic light-sensitive material 1) Measurement of sensitivity Using a filter having the filter characteristics shown in FIG. 2 of Japanese Patent Application No. 4-193432, a tungsten light source having a color temperature of 2854 K ° (545 nm by a filter) Light (corresponding to the main emission wavelength of the radiation intensifying screen used together) was used as the irradiation light to expose the photographic light-sensitive material, and its sensitivity was measured. That is, the above irradiation light is passed through the neutral step wedge 1 /
Exposure was carried out by irradiating the light-sensitive material for 20 seconds. After exposure, the photosensitive material was exposed to an automatic developing machine (Fuji Photo Film Co., Ltd., trade name FPM-5000) using the developer [A] described above at 35 ° C. for 25 seconds (total processing time 90
Developed). After peeling off the photosensitive layer on the side opposite to the exposed surface,
The density was measured, a characteristic curve was obtained, and the exposure amount required to obtain a density obtained by adding 0.5 to the minimum density (Dmin) was calculated from the characteristic curve. The exposure amount was shown in Table 2 as lux seconds. .
In calculating the exposure amount, the illuminance of the light emitted from the tungsten light source and transmitted through the filter is PI-3F.
The illuminance meter (rehabilitated) was measured.

2) Measurement of crossover A silver halide photographic light-sensitive material was used as a radiation intensifying screen A.
(A terbium-activated gadolinium oxysulfide phosphor (using a main emission wavelength: 545 nm, green light)) and black paper were sandwiched and X-ray was irradiated from the black paper side. The same X-ray source as that used in the evaluation of the intensifying screen was used. X-ray dose is changed by the distance method, and X
The line was irradiated. After irradiation, the light-sensitive material was developed in the same manner as in the above-described sensitivity measurement. The developed photosensitive material was divided into two, and the respective photosensitive layers were peeled off. The density of the photosensitive layer on the side in contact with the intensifying screen was higher than that on the opposite side. A characteristic curve is obtained for each photosensitive layer, and the average value of the sensitivity difference (ΔlogE) in the linear portion (density 0.5 to 1.0) of the characteristic curve is obtained. Over was calculated. Crossover (%) = 100 / (antilog (Δ logE)
+1) The same value was obtained even when the intensifying screen was changed to another one.

The calculated crossover (%) is shown in Table 2. Table 2 Photosensitive material Single-sided sensitivity (Dmin +0.5) Crossover Super HRS 0.0076 lux seconds 18% Photosensitive material I 0.0075 lux seconds 22% Photosensitive material II 0.0042 lux seconds 29%

3) Visual evaluation Chest phantom, three-phase 12-pulse 1 manufactured by Kyoto Chemical Co., Ltd.
00KVp (3mm thick aluminum equivalent filter installed), using X-ray source with focal spot size 0.6mm × 0.6mm, put phantom at 140cm distance, and then prevent scattered rays with grid ratio 8: 1 Photographing was performed by placing the grid, and then the combination of the light-sensitive material and the intensifying screen. The development processing was performed in the same manner as in the measurement of photographic characteristics.

A certain point in the lung field was determined, and the X-ray exposure amount was adjusted by changing the exposure time so that the density became 1.6. The finished chest phantom photograph was placed on the Schaukasten for visual evaluation. The visibility of the blood vessel shadow in the lung field was evaluated mainly, and the goodness was evaluated as ◯, the diagnosis was manageable as Δ, and the inability to be diagnosed as ×. Table 3 shows the above evaluation results.

[0044]

[Table 1]

Since the image forming method of the present invention has high system sensitivity, it can be seen that the amount of exposure to the human body can be reduced and the image quality is not impaired.

Claims (4)

[Claims] 1. A radiation image forming method comprising a silver halide photographic light-sensitive material and a radiation intensifying screen, wherein (1) at least one of the radiation intensifying screens comprises:
X-ray energy shows an absorption amount of 25% or more for X-rays with 80 KVp, and the contrast transfer function (CTF) is
A radiation intensifying screen having a spatial frequency of 1 / mm or more and 0.79 or more, and (2) the silver halide photographic light-sensitive material has the same main emission peak wavelength as that of the radiation intensifying screen specified in (1) above. Exposure with monochromatic light having a half-value width of 15 ± 5 nm and a developing solution of the following composition at a developing solution temperature of 35 ° C. and a developing time of 25 seconds. After the layer was peeled off and measured, the exposure amount required for the density obtained in the photosensitive layer to be a value obtained by adding 0.5 to the minimum density was 0.
An image forming method having a sensitivity of less than 010 lux seconds. Developer composition potassium hydroxide 21 g potassium sulfite 63 g boric acid 10 g hydroquinone 25 g triethylene glycol 20 g 5-nitroindazole 0.2 g glacial acetic acid 10 g 1-phenyl-3-pyrazolidone 1.2 g 5-methylbenzotriazole 005 g glutaraldehyde 5 g odor 4 g of potassium iodide 4 g of water was added to make 1 liter, and the pH was adjusted to 10.02. 2. The image forming method according to claim 1, wherein the silver halide photographic light-sensitive material has a crossover of 16% or more when the radiation intensifying screen defined in (1) above is used. 3. The crossover according to claim 2, wherein the crossover is 20.
% Or more. 4. The image forming method according to claim 3, wherein the sensitivity is less than 0.0045 lux seconds as an exposure amount.