JPH11316428A - Method and system for forming x-ray image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and surely obtain high-sharpness, high-resolution and high- quality X-ray image required for a mammography, the bones of limbs and the like, for example by using an inexpensive device. SOLUTION: By this X-ray image forming method, the X-ray image is captured to a flat panel detector 2 and fetched from the detector 2 as an image signal. In addition, a thermal developing photosensitive material fundamentally, including a reducer for photosensitive silver halide, a non-photosensitive reducing silver source and a silver source is used so that the image signal is converted into a light intensity change, recorded on photosensitive silver halide grains and heated under the existence of the reducer for the non-photosensitive reducing silver source and the silver source. Thus, the X-ray image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray image forming method and an X-ray image forming system used for, for example, X-ray mammography and imaging of limb bones.

[0002]

2. Description of the Related Art As an X-ray image forming system used for mammography, X-ray imaging of limb bones, etc., an X-ray image is captured by a flat panel detector, and the X-ray image is extracted as an image signal from the flat panel detector.
For example, thermal fusion transfer using a thermal head is performed.

[0003]

By the way, an X-ray image is captured by a flat panel detector, and the X-ray image is extracted as an image signal from the flat panel detector.
Although a detector having extremely high sharpness is used in the line image forming system, sufficient sharpness cannot be obtained by, for example, a thermal fusion transfer method using a thermal head.

[0004] In the hot-melt transfer method, for example, there is a method in which a recording sheet is superimposed and transferred on an image receiving film using a recording drum. However, there are problems such as an expensive apparatus and slow image formation. The high sharpness possessed by the panel detector cannot be realized with an inexpensive device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is capable of quickly, reliably and inexpensively producing high-quality X-ray images of high sharpness and high resolution required for mammography and limb bones, for example. It is an object of the present invention to provide an X-ray image forming method and an X-ray image forming system which can be obtained by a simple apparatus.

[0006]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention has the following constitution.

According to the first aspect of the present invention, there is provided a method for capturing an X-ray image by a flat panel detector, extracting the X-ray image from the flat panel detector as an image signal, and using a photosensitive silver halide, a non-photosensitive reducing agent. Using a photothermographic material basically containing a silver source and a reducing agent for the silver source,
The image signal is converted into a change in light intensity, recorded on photosensitive silver halide grains, and heated in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source to obtain an X-ray image. An X-ray image forming method, comprising: ].

According to the first aspect of the present invention, thermal development processing is performed by recording on photosensitive silver halide grains and heating in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source. By doing so, it is possible to quickly and reliably obtain a high-quality X-ray image with high sharpness and high resolution required for, for example, mammography and limb bones.

According to a second aspect of the present invention, there is provided an X-ray image forming system for capturing an X-ray image by a flat panel detector and extracting the X-ray image as an image signal from the flat panel detector. Instead of changing the light intensity, recording on the photosensitive silver halide grains of the photothermographic material, and heating in the presence of a non-photosensitive reducible silver source of the photothermographic material and a reducing agent for the silver source An X-ray image forming system comprising a heat developing device for obtaining an X-ray image. ].

According to the second aspect of the present invention, the photosensitive silver halide grains are recorded by a heat developing device and heated in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source. By subjecting the photothermographic material to heat development, high-quality X-ray images with high sharpness and high resolution required for, for example, mammography and limb bones can be obtained quickly, reliably, and at low cost. be able to.

According to a third aspect of the present invention, there is provided an image forming apparatus comprising: a heat transporting device for transporting the photothermographic material; and an exposure device for exposing and recording the photosensitive silver halide particles of the photothermographic material. Heating means for applying heat to a non-photosensitive reducible silver source of the photothermographic material and a reducing agent for the silver source; and control means for controlling the transport means, exposure means and heating means, 3. The X-ray image forming system according to claim 2, wherein an X-ray image is obtained by subjecting the developed photosensitive material to heat development. ].

According to the third aspect of the present invention, the photothermographic material is conveyed and exposed to and recorded on photosensitive silver halide grains, and the non-photosensitive reducible silver source and the reduction for the silver source are reduced. By heating the photothermographic material in the presence of an agent and subjecting the photothermographic material to thermal development processing, high-quality X-ray images with high sharpness and high resolution required for, for example, mammography and limb bones can be quickly and reliably obtained. In addition, it can be obtained with an inexpensive device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an X-ray image forming method and an X-ray image forming system of the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment. Clearly not.

FIG. 1 is a schematic configuration diagram of an X-ray image forming system, FIG. 2 is a schematic sectional view showing a flat panel detector (FPD), and FIG. 3 is a flat panel detector (FP).
It is a schematic plan view which shows D).

As shown in FIG. 1, the X-ray image forming system captures an image of a subject 60 with X-rays emitted from an X-ray tube 1 and converts the X-ray image into a flat panel detector (FP).
D) Capture in 2. This flat panel detector (F
An X-ray image is extracted from PD) as an image signal, image-processed by an image processing unit 3, and sent to a network 4. The network 4 includes a liquid crystal display 5 and a laser imager 6
Are connected to display an X-ray image on the liquid crystal display 5 or print and output the X-ray image by the laser imager 6.

A specific example of the FPD is disclosed in JP-A-6-342098.
Is disclosed. That is, the X-ray transmitted through the subject
A charge is generated in accordance with the X-ray intensity by being absorbed by a photoconductive layer such as a -Se layer and the amount of the charge is detected for each pixel.
Japanese Patent Application Laid-Open No. 9-90048 describes an example of another type of FPD.
As disclosed in Japanese Patent Application Laid-Open No. H11-229, an X-ray is absorbed by a phosphor layer such as an intensifying screen to generate fluorescence, and the intensity of the fluorescence is detected by a photodetector such as a photodiode provided for each pixel. is there. Other means for detecting fluorescence include CCD and C-MO.
There is also a method using an S sensor.

In particular, in the FPD of the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-342098, since the X-ray dose is directly converted into the charge amount for each pixel, the sharpness of the FPD is hardly degraded, and the image with excellent sharpness is obtained. Therefore, the effects of the X-ray image recording system and the X-ray image recording method of the present invention are large and suitable.

Flat panel detector (FPD) 2
Is configured as shown in FIG. 2 and FIG.

Flat panel detector (FPD) 2
Is, as shown in FIG. 2, a photoconductive layer 2
1, a dielectric layer 22, and a front conductive layer 23 are sequentially laminated. A plurality of first micro-conductive electrode microplates 24 are provided on the dielectric substrate layer 20, and the minimum pixel that can be resolved by the flat panel detector (FPD) 2 depending on the size of the first micro-conductive electrode microplate 24. Is determined. On the plurality of first minute conductive electrode microplates 24, a capacitance dielectric material 25 is formed. An X-ray image can be formed even if the dielectric layer 22 is removed from the flat panel detector (FPD) 2, and the present invention can be realized.
There is a possibility that the retention of the amount of charge accumulated in step 6 and the sharpness of the X-ray image may be slightly reduced.

Further, a plurality of transistors 29 each having two electrodes 26 and 27 and a gate 28 are stacked on the dielectric substrate layer 20. Further, on the dielectric substrate layer 20, a plurality of second minute conductive electrode microplates 30 are stacked.

As shown in FIG. 3, at least one transistor 29 includes a plurality of second minute conductive electrode microplates 30 connected to an X address line 41 and a Y sense line 4.
2 connected. The charge storage capacitor 36 is formed by the first micro-conductive electrode microplate 24, the second micro-conductive electrode microplate 30, and the capacitance dielectric material 25. The second microconductive electrode microplate 30 is also connected to the electrode 27 of the transistor 29. The first micro conductive electrode micro plate 24 is connected to ground.

Transistor 29 acts as a bidirectional switch, depending on whether a bias voltage has been applied to the gate via X address line 41 or not.
A current flows between the capacitor 2 and the charge storage capacitor 36.

A conductive electrode or X address line 41 and a conductive electrode or Y sense line 42 are arranged in a space between the plurality of second micro-conductive electrode microplates 30. The X address line 41 and the Y sense line 42 are arranged so as to be substantially orthogonal to each other as shown in the figure. The X address lines 41 and the Y sense lines 42 are individually accessible along the sides or edges of the flat panel detector (FPD) 2 through leads or connectors.

Each of the X address lines 41 is sequentially addressed by applying a bias voltage to the line, and thus to the gate of the transistor 29 connected to the addressed X address line 41. As a result, the transistor 29 is turned on, and the charge stored in the corresponding charge storage capacitor 36 flows to the Y sense line 42 and to the input side of the charge detector 46. Charge detector 46 generates a voltage output proportional to the charge detected on Y sense line 42. The output of the charge detector 46 is sampled sequentially to obtain an image signal representing the charge distribution of the microcapacitors on the addressed X address line 41, where each microcapacitor has 1
Represents one image pixel. When a signal is read from a certain pixel line on the X address line 41, the charge amplifier is reset through the reset line 49. Next X
Address line 41 is addressed, and the process comprises:
All charge storage capacitors 36 are sampled and repeated until the entire image is read.

In the laser imager 6, the heat developing device 7
And is shown in FIG. FIG. 4 is a schematic configuration diagram of the heat developing device.

The thermal developing device 7 includes a transporting unit 70 for transporting the photothermographic material P, an exposing unit 71 for exposing and recording the photosensitive silver halide particles of the photothermographic material P, A heating means 72 for applying heat to the non-photosensitive reducible silver source and the reducing agent for the silver source; and a control means 73 for controlling the transporting means 70, the exposing means 71 and the heating means 72. An X-ray image is obtained by thermally developing the material P.

In the thermal developing device 7, the photothermographic material P
And recording by exposing the photosensitive silver halide grains,
By heating in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source, and thermally developing the photothermographic material P,
For example, high-quality X-ray images with high sharpness and high resolution required for mammography, limb bones, and the like can be obtained quickly, reliably, and at low cost.

Hereinafter, the photothermographic material of the present invention will be described in detail. The photothermographic material of the present invention basically contains a photosensitive silver halide, a non-photosensitive reducible silver source, and a reducing agent for the silver source, and forms an image using a photothermographic processing method. Is what you do. For details of the photothermographic material, see, for example, U.S. Patent Nos. 3,152,904 and 3,457,
No. 075, and D.A. “Dry Silver Photographic Materials (Dry Silver P) by Morgan
photographic Material) ”and D.C.
Morgan and B.A. Shelley
y) "Heat treated silver system (The
rally Processed Silver S
systems) (Imaging Processes and Materials (imaging Process)
es and Materials) Neblettc
Eighth Edition, Sturge, V.S. Walworth, A .; Shep
p) Edit, page 2, 1969).

The photosensitive silver halide grains in the present invention will be described. In the present invention, the average particle size is preferably small, and more preferably 0.1 μm or less, in order to suppress white turbidity after image formation and obtain good image quality. The term “grain size” as used herein refers to the length of a ridge of a silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case where the silver halide grains are tabular grains, the diameter refers to a diameter when converted into a circular image having the same area as the projected area of the main surface. The silver halide is preferably monodispersed. Here, the monodispersion means that the degree of monodispersion determined by the following equation is 40 or less. The particle size is more preferably 30 or less, and particularly preferably 0.1 or more and 20 or less.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100 The shape of silver halide grains is cubic, octahedral, tabular, spherical, rod-like, potato-like. In particular, cubic grains and tabular grains are preferred in the present invention. When tabular silver halide grains are used, the average aspect ratio is preferably 2 or more and 1 or more.
00 or less, more preferably 3 or more and 50 or less. These are disclosed in U.S. Patent Nos. 5,264,337 and 5,314,
No. 798, 5,320,958, etc., and the desired tabular grains can be easily obtained. Further, grains having rounded corners of silver halide grains can also be preferably used. Although the outer surface of the silver halide grains is not particularly limited, it is preferable that the ratio occupied by the Miller index [100] plane is high, and this ratio is 50% or more.
Further, it is preferably at least 70%, particularly preferably at least 80%. The ratio of the [100] plane of the Miller index is determined by T.M. using the dependence of the adsorption of the sensitizing dye on the [111] plane and the [100] plane. Tani, J .; Imaging Sci. 2
9, 165 (1985).

The halogen composition is not particularly limited.
Any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide may be used. In the present invention, silver bromide or silver iodobromide can be preferably used. Particularly preferred is silver iodobromide, and the silver iodide content is preferably from 0.1 mol% to 40 mol%, more preferably from 0.1 mol% to 20 mol%. The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be changed continuously, but as a preferred example, the silver iodide content in the grains is preferred. High silver iodobromide grains can be used. Preferably, silver halide grains having a core / shell structure can be used.

The photographic emulsion used in the present invention is described in US Pat. G
Chimieet Physique by Lafkides
e Photographique (Paul Mo
ntel, 1967); F. Photographic Emulsion Ch by Duffin
emistry (The Focal Press
Published in 1966); L. Zelikman et
Making and Coating photo by al
optic Emulsion (the Foc
al press, 1964) and the like. That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and a method of reacting a soluble silver salt with a soluble halide may be any one of a one-sided mixing method, a double-sided mixing method, a combination thereof and the like. Good. The silver halide may be added to the image forming layer by any method, in which case the silver halide is arranged close to the reducible silver source.

The silver halide may be prepared by converting a part or all of the silver in the organic acid silver by the reaction between the organic acid silver and the halide ion to silver halide. It may be prepared in advance and added to a solution for preparing an organic silver salt, or a combination of these methods is possible, but the latter is preferred. Generally, the silver halide is preferably contained in an amount of 0.75 to 30% by weight based on the organic silver salt.

The silver halide grains used in the present invention preferably contain a complex of a metal selected from the group consisting of Fe, Co, Ru, Rh, Re, Os, and Ir. May be used in combination of two or more. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻² mol per mol of silver, more preferably in the range of 1 × 1 ⁻⁸ mol to 1 × 10 ⁻⁴ mol.

In the present invention, the transition metal complex is preferably a six-coordinate complex represented by the following general formula.

In the formula [ML ₆ ] ^m , M is a transition metal selected from elements of Groups 6 to 10 of the periodic table, L is a bridging ligand, and m is 0, 1-, 2-, 3-.
Or 4-. Specific examples of the ligand represented by L include halides (fluorides, chlorides, bromides, and iodides), cyanides, cyanates, thiocyanates, selenocyanates, tellurocyanates, azides, and aquos. Examples include ligand, nitrosyl, thionitrosyl and the like, and preferred are aquo, nitrosyl and thionitrosyl.
If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

As M, preferred specific examples in the case of rhodium (Rh), ruthenium (Ru), rhenium (Re) and osmium (Os) are shown.

[0038] 1: [RhCl _6] ^3- 2: [RuCl _6] ^3- 3: [reci _6] ^3- 4: [RuBr _6] ^3- 5: [OSCI _6] ^3- 6: [CRCI _6] ^{4 -} 7: [Ru (No) CI _5] ^2- 8: [RuBr ₄ (H ₂ O)] ^2- 9: _{[Ru (NO) (H 2 O} ) CI 4 ] ^- 10: [RhC1 ₅ (H ₂ O)] ^2- 11: [Re (NO) CI _5] ^2- 12: [Re (NO) CN _5] ^2- 13: [Re (NO) cICN _4] ^2- 14: [Rh (NO) ₂ CI _4] ^- 15: _{[Rh (NO) (H 2 O} ) C1 4 ] ^- 16: [Ru (NO) CN _5] ^2- 17: [Fe (CN) _6] ^3- 18: [Rh (NS) CI _5] ^2- 19: [Os (NO) CI _5] ^2- 20: [Cr (NO) CI _5] ^2- 21: [Re (NO) CI _5] ^- 22: [Os (NS) CI ₄ (TeCN )] ^2-23 : [Ru (NS) CI _5] ^2- 24: _{[Re (NS) CI 4 (SeCN} ) ] ^2- 25: [Os (NS) CI (SCN) 4 ] ^2- 26: [Ir (NO) CI _5] For the compounds of ^2- cobalt and iron, hexacyano metal complexes can be preferably used. Specific examples are described below.

27: [Fe (CN) ₆ ] ^4- 28: [Fe (CN) ₆ ] ³ -29: [Co (CN) ₆ ] ^3-When providing these metal ions or complex ions, the compound: It is preferably added during silver halide grain formation and incorporated into silver halide grains.Preparation of silver halide grains, i.e., nucleation, growth, physical ripening, and addition at any stage before and after chemical sensitization. It is preferably added at the stage of nucleation, growth and physical ripening, and most preferably at the stage of nucleation. Upon addition, the compound may be added in several divided portions, and may be uniformly contained in silver halide grains.
No. 03, JP-A-2-306236 and JP-A-3-16754
No. 5, No. 4-76534, No. 6-110146, No. 5-273683, etc., the particles can be contained in the particles with distribution. Preferably, a distribution can be provided inside the particles. These metal compounds can be added by dissolving them in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). Aqueous solution or metal compound and N
a method in which an aqueous solution in which aCl and KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a third method in which the silver salt solution and the halide solution are simultaneously mixed. A method of preparing silver halide grains by adding as an aqueous solution and mixing three solutions, a method of charging a required amount of an aqueous solution of a metal compound into a reaction vessel during grain formation, or a method of preparing a metal halide in advance during silver halide preparation. There is a method in which another silver halide grain doped with ions or complex ions is added and dissolved.

In particular, a method of adding an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble halide solution. When it is added to the particle surface, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or at the end of physical ripening, or at the time of chemical thermoforming.

The photosensitive silver halide grains can be desalted by a known desalting method such as a noodle method, flocculation method, ultrafiltration method, and electrodialysis method.

The photosensitive silver halide grains in the present invention are preferably chemically sensitized. Examples of the sensitization method include sulfur sensitization, selenium sensitization, tellurium sensitization, noble metal sensitization,
Known sensitization methods such as reduction sensitization can be used. These sensitization methods can be used in combination of two or more. For sulfur sensitization, thiosulfates, thiourea compounds, inorganic sulfur and the like can be used. Compounds preferably used for selenium sensitization and tellurium sensitization include:
Compounds described in JP-A-9-230527 can be exemplified. Compounds preferably used in the noble metal sensitization method include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide,
Alternatively, U.S. Pat. No. 2,448,060, British Patent No. 618,
No. 061 and the like. Specific compounds of the reduction sensitization method include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, and the like. Further, reduction sensitization can be achieved by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less.

The photothermographic material of the present invention contains, as spectral sensitizing dyes, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes. Etc. can be used. For example, JP-A-63-159
No. 841, No. 60-140335, No. 63-2314
No. 37, No. 63-259,651 and No. 63-30424
No. 2, 63-15245, U.S. Pat.
No. 414, No. 4,740,455, No. 4,74
No. 1,966, No. 4,751,175, No. 4,8
Sensitizing dyes described in JP 35,096 can be used.

Useful sensitizing dyes for use in the present invention include, for example, Research Disclosure It
em 17643 IV-A (p.
23), How Item 1831, Section X (August 1978
Monthly p437) or in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers and scanners can be advantageously selected. For example, JP-A-9-3407
Compounds described in Nos. 8, 9-54409 and 9-80679 are preferably used.

Useful cyanine dyes are, for example, cyanine dyes having a basic nucleus such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyrididine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus. Preferred among the famous merocyanine dyes are, in addition to the above basic nuclei, acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedion nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus. Including.

These sensitizing dyes may be used alone or in combination, and a combination of sensitizing dyes is often used particularly for supersensitization. In addition to the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization. Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in Research Disclosure (Re
search Disclosure) Volume 176 17
J. 643 (published December 1978), page 23, 1V,
Alternatively, the aforementioned Japanese Patent Publication Nos. 9-25500 and 43-493.
No. 3, JP-A-59-19032 and JP-A-59-19224.
No. 2, etc.

In the present invention, the organic silver salt is a reducible silver source, and a silver salt of an organic acid or a heteroorganic acid containing a reducible silver ion source, particularly a long chain (10 to 30, preferably 15 to 28) The silver salt of an aliphatic carboxylic acid having (the number of carbon atoms) is preferred. Organic or inorganic silver salt complexes wherein the ligand has a complex stability constant for silver ions of 4.0 to 10.0 are also useful. Examples include: silver salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid,
Palmitic acid, lauric acid, oleic acid, caproic acid,
Salts of myristic acid, palmitic acid, maleic acid, linoleic acid, etc.): carboxyalkylthiourea salt of silver (for example, 1- (3-carboxypropyl) thiourea, 1-
(3-carboxypropyl) -3,3-dimethylthiourea, etc.): silver complex of a polymer reaction product of aldehyde and hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.), hydroxy-substitution) Acids (e.g., salicylic acid, benzoic acid, 3.5-dihydroxybenzoic acid, 5.5
-Thiodisalicylic acid), silver salts or complexes of thio salts (eg, 3- (2-carboxyethyl) -4-hydroxymethyl-4- (thiazoline-2-thioene, and 3-carboxymethyl-4-thiazoline-2) -Thioene), imidazole, pyrazole, urazole, 1,2,4-thiazole, and nitrogen acid and silver selected from 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole Complex or salt with:
Silver salts such as saccharin, 5-chlorosalicylaldoxime: and silver salts of mercaptides, examples of suitable silver salts are
described in Science Disclosure Nos. 17029 and 29963, and a particularly preferred silver source is silver behenate.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, and includes a forward mixing method, a reverse mixing method, a simultaneous mixing method, and a method described in JP-A-9-12764.
A controlled double jet method as described in No. 3 is preferably used.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, but a needle crystal having a short axis and a long axis is preferable. As is well known in photosensitive silver halide photosensitive materials, the inverse relationship between the size of silver salt crystal grains and their covering power also holds in the photothermographic material of the present invention. If the organic silver salt particles as the image forming portion are large, it means that the covering power is small and the image density is low. Therefore, it is necessary to reduce the size of the organic silver salt.

In the present invention, the minor axis is 0.01 μm or more and 0.20 μm or less, and the major axis is 0.10 μm or more and 5.0 μm or less.
The following are preferable, and the short axis is preferably 0.01 μm to 0.15 μm, and the long axis is preferably 0.10 μm to 4.0 μm.
The particle size distribution of the organic silver salt is preferably monodispersed. The monodispersion is preferably a percentage of a value obtained by dividing the standard deviation of the length of each of the short axis and the long axis by each of the short axis and the long axis.
It is preferably at most 00%, more preferably at most 80%, even more preferably at most 50%. The shape of the organic silver salt can be measured by increasing the dispersion of the organic silver salt with a transmission electron microscope. Another method of measuring monodispersity is to determine the standard deviation of the volume-weighted average diameter of the organic silver salt, and the percentage of the value divided by the volume-weighted average diameter (coefficient of variation).
Is preferably 100% or less, more preferably 80% or less, and still more preferably 50% or less. As a measuring method, for example, an organic silver salt dispersed in a liquid is irradiated with a laser beam, and the autocorrelation coefficient with respect to the time change of the fluctuation of the scattered light is obtained from the particle size (volume weight average diameter) obtained. be able to. The coating amount of the organic silver salt, especially the organic acid silver in the light-sensitive material of the present invention,
0.5 to 5.0 g per ² is preferable, and more preferably 1.0 to 5.0 g.
~ 3.0 g is preferred.

Examples of the reducing agent suitable for the photothermographic material of the present invention are described in US Pat. Nos. 3,770,448 and 3,7,448.
Nos. 73,512, 3,593,863 and Res
Ear Disclosure No. 17029 and 2
9963, and includes the following.

Aminohydroxycycloalkenonone compounds (eg, 2-hydroxypiperidino-2-cyclohexenone): aminoreductones esters (eg, piperidinohexoseductactone monoacetate) as precursors of reducing agents ): N-hydroxyurea derivative (for example, Np-methylfernyl-
N-hydroxyureas): hydrazones of aldehydes or ketones (eg, anthracenaldehyde phenylhydrazone): phosphoramide phenols; phosphamide anilines: polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone) And (2,5-dihydroxy-phenyl) methyl sulfone): sulfhydroxamic acids (for example, benzenesulfhydroxamic acid): sulfonamidoanilines (for example, 4- (N-methanesulfonamido) aniline): 2-tetra Zolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone): Tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline): Amido Synths: azines (eg, a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid): a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine: hydroxanoic acids: a combination of azines and sulfonamidophenols , Α-cyanophenylacetic acid derivative: combination of bis-β-naphthol and 1,3-dihydroxybenzene derivative: 5-pyrazolones: sulfonamidophenol reducing agent: 2-phenylindane-1,
3-dione and the like: chroman: 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine): bisphenols (for example, bis (2-hydroxy-3- t-butyl-5
-Methylphenyl) methane, bis (6-hydroxy-m
-Tri) mesitol, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
4,5-Ethylidene-bis (2-t-butyl-6-methyl) phenol, UV-sensitive ascorbic acid derivatives and 3-pyrazolidones, among which particularly preferred reducing agents are hindered phenols. Examples of the hindered phenols include compounds represented by the following general formula (A).

[0053]

Embedded image

In the formula, R represents a hydrogen atom or a group having 1 to 1 carbon atoms.
10 alkyl groups (for example, -C4H9,2,4,4-
R ′ and R ″ represent an alkyl group having 1 to 5 carbon atoms (eg, methyl, ethyl, t-
Butyl).

Specific examples of the compound represented by formula (A) are shown below. However, the present invention is not limited to the following compounds.

[0056]

Embedded image

[0057]

Embedded image

The amount of the reducing agent such as the compound represented by the formula (A) is preferably 1 to 1 mol per silver.
It is from × 10 ^-2 to 10 mol, especially from 1 × 10 ^{-2 to} 1.5 mol. Binders suitable for the photothermographic material of the present invention are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic, and poly (vinyl alcohol). , Hydroxyethylcellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acryls), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene) −
Maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters),
There are poly (urethanes), phenoxy resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and poly (amides). It may be hydrophilic or non-hydrophilic.

In the present invention, the amount of binder in the photosensitive layer is 1.5 to 1 for the purpose of preventing dimensional fluctuation after thermal development.
It is preferably 0 g / m ² . More preferably, it is 1.7 to 8 g / m ² . If it is less than 1.5 g / m ² , the density of the unexposed portion will increase significantly, and may not be usable.

In the present invention, a matting agent is preferably contained on the photosensitive layer side, and in order to prevent damage to the image after thermal development, it is preferable to provide a matting agent on the surface of the photosensitive material. The matting agent is preferably contained in a weight ratio of 0.5 to 10% with respect to all binders on the emulsion layer side.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as inorganic substances, silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, etc., and alkali described in British Patent No. 1,173,181 etc. An earth metal or a carbonate such as cadmium or zinc can be used as a matting agent. As organic substances, starch described in U.S. Pat. No. 2,322,037, etc.,
Belgian patent 625,451 and British patent 981,
No. 198, etc., JP-B-44-36
No. 43, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, etc., polyacrylonitrile described in US Pat. No. 3,079,257, US Pat. No. 3,02.
An organic matting agent such as polycarbonate described in JP-A-2,169 or the like can be used.

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the spherical shape of the matting agent refers to the diameter converted into the spherical shape.

The matting agent used in the present invention preferably has an average particle size of 0.5 μm to 10 μm, more preferably 1.0 μm to 8.0 μm. The matting agent has a coefficient of variation of the particle size distribution of preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less.

Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

(Standard deviation of particle size) / (average value of particle size) × 100 The matting agent according to the present invention can be contained in any constituent layer, but is preferably used in order to achieve the object of the present invention. Is a constituent layer other than the photosensitive layer, more preferably the outermost layer as viewed from the support. The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed before the drying is completed after applying the coating solution. May be. When a plurality of types of matting agents are added, both methods may be used in combination.

The photothermographic material of the present invention, which forms a photographic image by heat development, comprises a reducible silver source (organic silver salt), a catalytically active amount of silver halide, a hydrazine derivative, a reducing agent, It is preferable that the photothermographic material contains a color tone agent for suppressing the color tone of silver, if necessary, usually in a state dispersed in an (organic) binder matrix.

The photothermographic material of the present invention is stable at room temperature, but is developed by heating to a high exposure temperature (for example, 80 ° C. to 140 ° C.). Heating produces silver through an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is accelerated by the catalytic action of the latent image generated on the silver halide upon exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image. This reaction process proceeds without supplying a processing liquid such as water from the outside.

The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. A filter layer may be formed on the same side as or opposite to the photosensitive layer to control the amount or wavelength distribution of light passing through the photosensitive layer, or the photosensitive layer may contain a dye or pigment. . As the dye, compounds described in JP-A-8-201959 are preferred. The photosensitive layer may be composed of a plurality of layers, and the sensitivity may be changed to a high-sensitive layer / low-sensitive layer or a low-sensitive layer / high-sensitive layer for controlling the floor. Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other layers. The photothermographic material of the invention may contain, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, and a coating aid.

It is preferable to add a color tone agent to the photothermographic material of the present invention. Toning agents are disclosed in US Pat.
Nos. 0254, 3847612 and 41232
No. 82, it is a material well known in the photographic art. Examples of suitable toning agents are Research Diss
No. 17029, which includes the following:

Imides (eg, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (eg, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione): nafuralimides (for example, N-hydroxy-1,8-naphthalimide): cobalt complex (for example, hexamine trifluoroacetate of cobalt), mercaptans, (for example, 3-mercapto-1, 2,4-triazole): N
-(Aminomethyl) aryldicarboximides,
(Eg, N- (dimethylaminomethyl) phthalimide): a combination of blocked pyrazoles, isothiuronium derivatives and certain photobleaches (eg, N, N′-hexamethylene (1-carbamoyl-3, 5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate), and 2-
(Combination of (tribromomethylsulfonyl) benzothiazole): Merocyanine dye (for example, 3-ethyl-
5-((3-ethyl-2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene)-
2-thio-2,4-oxazolidinedione): phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone) And 2,3-dihydro-1,4-phthalazinedione): a combination of phthalazinone and a sulfinic acid derivative (eg, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + p-trisulfonic acid) Sodium): phthalazine + phthalic acid combination: phthalazine (including an adduct of phthalazine) and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or 0-phenylene acid derivative and its anhydride (for example, phthalic acid) Acid, 4-methylphthalic acid, 4-nitrophthalic acid and tet Combination of at least one compound selected from the chlorophthalic anhydride): quinazoline compounds, benzoxazine, Narutokisajin derivatives, Benzuokisaji 2,4-diones (e.g., 1,
3-benzoxazine-2,4-dione): pyrimidines and asymmetric-triazines (eg, 2,4-benzoxazine-2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (eg, 3,6 -Dimercapto-1,4-diphenyl-1H, 4H-2,3a,
5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

The present invention contains a mercapto compound, a disulfide compound, and a thione compound in order to suppress or accelerate development to control development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. Can be done. When a mercapto compound is used in the present invention, any structure may be used, but ArSM, Ar-
Those represented by SS-Ar are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or a condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole,
Benzoterzole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine, pyrazine,
Pyridine, purine, quinoline or quinazolinone.

The heteroaromatic ring includes, for example, halogen (eg, Br and Cl) hydroxy, amino, carboxy,
Alkyl, (eg, having one or more carbon atoms, preferably having 1 to 4 carbon atoms) and alkoxy (eg, having one or more carbon atoms, preferably having 1 to 4 carbon atoms) And a group selected from the group consisting of substituents. Examples of the mercapto-substituted heteroaromatic compound include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzimidazole, 6-ethoxy-2-mercaptobenzothiazole,
2,2'-dithiobisbenzothiazole, 3-mercapto-1,2,4-triazole, 4,5-diphenyl-
2-imidazole thiol, 2-mercaptoimidazole, 1-ethyl-2-murcaptobenzimidazole,
2-mercaptoquinone phosphorus, 8-mercaptopurine, 2
-Mercapto-4- (3H) quinazolinone, 7-trifluoromethyl-4-quinolinethiol, 2,3,5,6
-Tetrachloro-4-pyridinethiol, 4-amino-
6-hydroxy-2-mercaptopyridimine monohydrate, 2-amino-5-mercapto-1,3,4-thiadiazole, 3-amino-5-mercapto-1,2,4
-Triazole, 4-hydroxy-2-mercaptopyrimidine, 2-mercaptopyrimidine, 4,6-diamino-2mercaptopyrimidine, 2-mercapto-4-methylpyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,2 4-triazole, 2-mercapto-
Examples thereof include 4-phenyloxazole, but the present invention is not limited thereto. The addition amount of these mercapto compounds is 0.001 per mole of silver in the emulsion layer.
To 1.0 mol, more preferably 1 mol of silver.
The amount is 0.01 to 0.3 mol per mol.

What is known as the most effective antifoggant is mercury ion. The use of a mercury compound as an antifoggant in a light-sensitive material is disclosed in, for example, US Pat. No. 3,589,903. However, mercury compounds are environmentally unfriendly. Examples of the non-mercury antifoggant include U.S. Pat. Nos. 4,546,075 and 4,452,885 and JP-A-59-572.
No. 34 are preferred.

Particularly preferred non-mercury antifoggants are disclosed in US Pat. Nos. 3,874,946 and 4,756,993.
No. 9, a compound such as -C (X1) (X
2) A heterocyclic compound having one or more substituents represented by (X3) (where X1 and X2 are halogen and X3 is hydrogen or halogen). Examples of suitable antifoggants include paragraphs [0062] to JP-A-9-90550.
The compounds described in [0063] are preferably used.

Further suitable antifoggants are disclosed in US Pat. No. 5,028,523 and EP 631,176.

In the photosensitive layer according to the present invention, a polyhydric alcohol (for example, US Pat. No. 29
Glycerin and diols of the type described in U.S. Pat. No. 60404) U.S. Pat.
Fatty acids or esters described in British Patent No. 9550
For example, the silicone resin described in No. 61 can be used.

A hardener may be used for each layer such as the photosensitive layer, the protective layer and the back layer of the present invention. Examples of hardeners include:
Isocyanate compounds, epoxy compounds described in U.S. Pat. No. 4,910,0042 and the like;
For example, vinylsulfone-based compounds described in JP-A-89048 and the like are used.

In the present invention, a surfactant may be used for the purpose of improving coating properties and charging. As an example of the surfactant, any of anionic, cationic, betaine, nonionic, and fluorine-based surfactants can be appropriately used. Specifically, Japanese Patent Application Laid-Open No. Sho 62-170950, U.S. Pat.
No. 82504, etc., a fluoropolymer surfactant,
JP-A-60-244945, JP-A-63-18813
No. 5, fluorinated surfactants described in US Pat.
85965 and the like; polyalkylene oxides and anionic surfactants described in JP-A-6-301140 and the like.

The photographic emulsion for thermal development in the present invention employs various coating methods including a dip coating method, an air knife coating method, a flow coating method, and an extrusion coating method using a hopper of the type described in US Pat. No. 2,681,294. be able to. If necessary, two or more layers can be applied simultaneously by the methods described in U.S. Pat. No. 2,761,791 and British Patent No. 8,370,955.

The support used in the present invention may be a plastic film (for example, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate) in order to obtain a predetermined optical density after development and to prevent image deformation after development. , Polyethylene naphthalate).

Among them, preferred supports include polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene naphthalate (hereinafter abbreviated as PEN), and plastics containing a styrene-based polymer having a syndiotactic structure (hereinafter abbreviated as SPS). Support.
The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

A plastic support which has been heat-treated can also be used. The plastics to be employed include the above-mentioned plastics. The heat treatment of the support means that after forming these supports and before the photosensitive layer is applied, at a temperature higher than the glass transition point of the support by 30 ° C. or higher, preferably by 35 ° C. or higher. It is more preferable to heat at a temperature higher than 40 ° C. However, the effect of the present invention cannot be obtained by heating at a temperature exceeding the melting point of the support.

Next, the plastic used will be described.

PET is a polyester in which all of the polyester components are made of polyethylene terephthalate. In addition to polyethylene terephthalate, terephthalic acid, naphthalene-2,6-dicarboxylic acid, isophthalic acid, butylene dicarboxylic acid, and 5-sodium sulfo acid are used as acid components. A polyester containing a modified polyester component of isophthalic acid, adipic acid or the like and a glycol component of ethylene glycol, propylene glycol, butanediol, cyclohexane dimethanol or the like in an amount of 10 mol or less of the entire polyester may be used.

Examples of the PEN include polyethylene 2,6 naphthalate, copolymerized polyesters composed of terephthalic acid, 2-6 naphthalenedicarboxylic acid and ethylene glycol, and polyesters containing a mixture of two or more of these polyesters as main components. Is preferred. Also,
Further, another copolymer component may be copolymerized, or another polyester may be mixed.

SPS is a polystyrene having steric regularity unlike ordinary polystyrene (atactic polystyrene). The regular stereoregular structural part of the SPS is called a racemo chain, and it is preferable that there are more regular parts such as two, three, five, or more. 85% in chain
It is preferable that the ratio is 75% or more for three chains, 50% or more for five chains, and 30% or more for more chains. SPS
Can be carried out according to the method described in JP-A-3-131843.

As the method for forming a film and the method for producing an undercoat according to the present invention, known methods can be used. Preferably, paragraph No. [0030] of JP-A-9-50094 is used.
To [0070].

[0088]

As described above, according to the first aspect of the present invention, a photothermographic method basically containing a photosensitive silver halide, a non-photosensitive reducible silver source and a reducing agent for the silver source. Using a material, the image signal is converted into a change in light intensity, recorded on photosensitive silver halide grains, and heated and heated in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source. By performing the development processing, it is possible to quickly and reliably obtain a high-quality X-ray image with high sharpness and high resolution required for, for example, mammography and limb bones.

According to the second aspect of the present invention, the photosensitive silver halide grains are recorded by a heat developing apparatus, and heated in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source. By subjecting the photosensitive material to heat development processing, high-quality X-ray images of high sharpness and high resolution required for, for example, mammography and limb bones can be obtained quickly, reliably, and at low cost. .

According to a third aspect of the present invention, there is provided a photothermographic material which is conveyed, exposed to light-sensitive silver halide grains and recorded, and comprises a non-photosensitive reducible silver source and a reducing agent for the silver source. Heating the photothermographic material down and heat-developing the photothermographic material can quickly and reliably produce high-quality X-ray images with high sharpness and high resolution required for mammography and limb bones, for example, at a low cost. Can be obtained with a simple device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an X-ray image forming system.

FIG. 2 is a schematic sectional view showing a flat panel detector (FPD).

FIG. 3 is a schematic plan view showing a flat panel detector (FPD).

FIG. 4 is a schematic configuration diagram of a heat developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray tube 2 Flat panel detector 3 Image processing part 4 Network 5 Liquid crystal display 6 Laser imager 7 Thermal developing device 70 Transport means 71 Exposure means 72 Heating means 73 Control means P Thermal developing photosensitive material

Claims (3)

[Claims] An X-ray image is captured by a flat panel detector, and an X-ray image is taken out from the flat panel detector as an image signal, and is used for a photosensitive silver halide, a non-photosensitive reducing silver source and a silver source. Using a photothermographic material basically containing a reducing agent, converting the image signal into a change in light intensity, recording on a photosensitive silver halide grain, a non-photosensitive reducible silver source, and a silver source X-ray image forming method comprising heating in the presence of a reducing agent for obtaining an X-ray image. 2. An X-ray image forming system for capturing an X-ray image by a flat panel detector and extracting the X-ray image as an image signal from the flat panel detector, wherein the X-ray image signal is converted into a change in light intensity. Thermal development in which an X-ray image is recorded by recording on the photosensitive silver halide particles of the photothermographic material and heating in the presence of a non-photosensitive reducible silver source and a reducing agent for the silver source of the photothermographic material An X-ray image forming system comprising an apparatus. 3. The photothermographic apparatus according to claim 1, wherein the photothermographic material includes a conveying unit for conveying the photothermographic material, an exposing unit for exposing and recording the photosensitive silver halide particles of the photothermographic material, A heating means for applying heat to the photosensitive reducible silver source and a reducing agent for the silver source; and a control means for controlling the transporting means, the exposing means and the heating means, wherein the photothermographic material is subjected to a heat development process. 3. An X-ray image forming system according to claim 2, wherein the X-ray image is obtained by performing the operation.