JPS599891B2 - Silver halide photosensitive material for radiography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a green-sensitized photographic silver halide light-sensitive material for carrying out radiation exposure by contacting an intensifying screen whose phosphor material emits light mainly in the green spectral range. It is related to.

As an X-ray recording material, an intensifying screen or a phosphor plate is often used together with a silver halide photographic film to increase the recording sensitivity to X-rays. Since exposure to an excessive amount of X-rays has a harmful effect on the human body, efforts are being made to increase recording sensitivity to X-rays in order to obtain effective radiographs with as little amount of X-rays as possible. One of the most effective and widely used methods is the method of recording a fluorescent image on a silver halide photosensitive material. Traditionally, phosphors used for this purpose include strontium-activated barium sulfate, lead-activated barium sulfate, silver-activated barium sulfate, and lead-activated barium sulfate. phosphors that emit blue fluorescence, such as calcium tungstate [CawO4], silver-activated zinc sulfide, and eurobium-activated barium phosphate [Ba3(PO4)2]. .

Particularly for medical purposes, sensitizing fluorescent screens used with radiographic silver halide materials actually contain barium sulfate activated by calcium tungstate or lead as the fluorophore. Recently, as the use of X-ray photography for medical purposes has increased, research has been carried out on sensitizing fluorescent screens with high luminous energy intensity.
In particular, it is known from research reports by Lockkeed Aircraft Corporation that rare earth oxysulfide and oxyhalide phosphors activated by other rare earth elements have high luminous energy intensity. . The phosphor or fluorescent substance used in the visible light emitting fluorescent screen used in the present invention preferably contains a substance of an element with an atomic number of 39 or 57 to 71 (for example, yttrium, gadolinium, lanthanum, cerium, etc.). .

Particularly useful are other rare earth activated rare earth oxysulfide and oxyhalide fluorophores, such as lanthanum or gadolinium oxybromides and oxychlorides activated with terbium or dysprosium, terbium, europium or It is an oxysulfide of lanthanum or gadolinium activated with a mixture of europium and samarium. Such rare earth fluorescent materials are disclosed in German Patent No. 1282819, French Patent No. 1540341, French Patent No. 1580544, French Patent No. 2021397, additional patent No. 94579 to French Patent No. 1473531, and US Patent No. 354612.
No. 8, No. 3418246, No. 3418247, and "Rare Earth Oxysulfide A report titled “Fluorescent Phosphor” and R.
E. Bukiyanan [IEEE Transactions on Nuclear Science (February 1972 issue, No. 8)
1-83). Such novel rare earth fluorophores, especially gadolinium and lanthanum oxysulfides and oxyhalides activated with other rare earths such as erbium, terbium and dysprosium, have high X-ray stopping or average absorption power and large luminescence. Radiation handlers use substantially lower X-ray doses!
make it possible to A lower amount of silver halide per unit area of a light-sensitive material is economically advantageous, and is generally advantageous in shortening processing time, particularly fixing time.

However, if a photographic material with a low silver halide content is used, the maximum density and contrast of the resulting image will be relatively low. Although fine grain emulsions are advantageous in obtaining high maximum densities, they have low photographic sensitivity and require large amounts of radiation exposure. Therefore, it is desirable to use an emulsion that is composed of highly sensitive silver halide grains and can provide sufficient maximum density and contrast even when containing a small amount of silver halide per unit area. According to the present invention, favorable results are obtained with photographic materials containing less than about 8.6 y of silver per square meter.

A so-called "crossover" occurs when a silver halide photographic material having silver halide layers on both sides of a support transparent to fluorescent light is brought into contact with an intensifying fluorescent screen during X-ray exposure. The light emitted by one such fluorescent screen not only produces a blackened image in the immediately adjacent silver halide emulsion layer, but also a significant amount of light passes through the relatively thick support and is reversed. It creates a blurred image in the side silver halide emulsion layer. This development is called "crossover." The degree of crossover substantially governs the quality of the image obtained in the photographic material. In ordinary radiation recording materials in which a relatively large amount of silver halide is used per unit area, there is little crossover, but in silver halide photosensitive materials with a small silver halide content per area, there is no crossover. The influence of over is large.

In order to reduce crossover, a method of containing a dye that absorbs light in the wavelength range emitted by a fluorescent intensifying screen in at least one layer of a silver halide photographic material is disclosed, for example, in JP-A-49-63424. It is known for such things.

The dyes used for these purposes are usually dyes used to prevent irradiation (light scattering in the emulsion layer).
It is well known that when these dyes are included in a silver halide emulsion, desensitization usually occurs. Even if a dye that does not chemically desensitize is used, some desensitization cannot be avoided due to the effect of light absorption. On the other hand, these dyes may be added to other hydrocolloid layers instead of the silver halide emulsion layer, but these dyes are usually water-soluble and therefore diffuse and migrate into the silver halide emulsion layer. Some desensitization due to the dye cannot be avoided. On the other hand, the base itself can be dyed to reduce crossover, but the commonly used dyeing of the base alone cannot sufficiently reduce crossover.

On the other hand, it is desirable that the X-ray photosensitive materials used (direct X-ray materials and indirect X-ray materials) be easy to handle, including development and fixing processes, and particularly preferably to be handled in a room that is as bright as possible.

This type of X-ray photographic material is handled under safe light using, for example, a Fujifilm Taki 7 safe light filter. The spectral transmittance curve of this F7 safelight filter is shown in FIG. That is, a radiographic material using a silver halide photographic emulsion should be highly sensitive to the emission of light by excitation of the radiation of the improved green phosphor described above, and low sensitive to safe light. is desirable. One of the objects of the present invention is to provide an X-ray fluorescent intensifying screen with a maximum emission in the green region of the spectrum, which has high sensitivity to emission, high safety light safety, and low crossover radiographic ( The purpose of the present invention is to provide a silver halide photosensitive material (particularly for medical X-ray photography).

Another object of the present invention is to achieve wavelength 400 by X-ray excitation.
X that emits fluorescence with more than half of its luminescent energy in the wavelength range of 100 nm or more, and the maximum luminescence is in the green region of the spectrum.
The object of the present invention is to provide a method for obtaining radiographs with good sharpness with a small radiation dose by combining a line fluorescent intensifying screen and a green-sensitized radiographic material having high sensitivity in the τ emission region.

The present inventors have discovered that the combination of specific sensitizing dye groups shown below effectively achieves the above objects of the present invention9.

That is, the object of the present invention is to combine at least one sensitizing dye represented by the following general formula (1) and at least one sensitizing dye represented by the general formula () to produce a halogenated sensitizing dye. This was achieved by incorporating it into a silver photographic emulsion. In the formula, A1 and A2 each represent a hydrogen atom, a halogen atom (e.g., chlorine atom, bromine atom, fluorine atom, iodine atom), a hydroxyl group, an alkoxy group (e.g., methoxy group, ethoxy group, etc.), an acyloxyl group (e.g., acetoxy group, etc.). group), alkoxycarbonylamino group (e.g., ethoxycarbonylamino group, etc.), cyano group, trifluoromethyl group, alkoxycarbonyl group (e.g.,
methoxycarbonyl group, ethoxycarbonyl group, etc.),
Alkylsulfonyl groups (e.g. methylsulfonyl groups), sulfamyl groups, alkylaminosulfonyl groups (
For example, it represents an ethylaminosulfonyl group, a diethylaminosulfonyl group, a morpholinosulfonyl group, a piperidinosulfonyl group, a morpholinocarbonyl group, a carbamoyl group, an alkylcarbonyl group. A, and A4
are hydrogen atoms, lower alkyl groups (e.g. methyl, ethyl, n-propyl, etc.), halogen atoms (
For example, chlorine atom, bromine atom, fluorine atom, iodine atom),
Alkoxy group (e.g. methoxy group, ethoxy group, etc.)
, hydroxyl group, phenyl group, substituted phenyl group (e.g., p-sulfophenyl group, etc.), carboxyl group, alkoxycarbonyl group (e.g., methoxycarbonyl group, ethoxycarbonyl group, etc.), cyano group, trifluoromethyl group, amino group ( (e.g., amino group, methylamino group, dimethylamino group, etc.), acylamido group (e.g., acetamido group, etc.), acyl group (e.g., acetyl group, etc.), acyloxyl group (e.g., acetoxy group, etc.), or alkoxycarbonylamino group (e.g., ethoxycarbonylamino group, etc.).

R,. R and R each represent an alkyl group (for example,
Substituted alkyl groups (e.g. vinylmethyl group), hydroxyalkyl groups (e.g. 2-hydroxyethyl group, 4-hydroxybutyl group), acetoxyalkyl groups, which are usually used in cyanine dyes (methyl group, ethyl group, n-propyl group, etc.) groups (e.g., 2-acetoxyethyl group, 3-acetoxypropyl group, etc.), alkoxyalkyl groups (e.g., 2-methoxyethyl group, 4-butoxybutyl group, etc.), carboxyalkyl groups (e.g., 2-carboxyethyl group, 3-carboxyprobyl group, 2-(2-carboxyethoxy)ethyl group, etc.), sulfoalkyl group (
For example, 2-sulfoethyl group, 3-sulfopropyl group,
3-sulfobutyl group, 4-sulfobutyl group, 2-hydroxy-3-sulfopropyl group, 2-(3-sulfopropoxy)ethyl group, 2-acetoxy-3-sulfopropyl group, 3-methoxy-2-(3-sulfopropyl group) propoxy)propyl group, 2-[2-(3-sulfopropoxy)ethoxy]
ethyl group, 2-hydroxy-3-(3'-sulfopropoxy)propyl, p-sulfophenethyl group, p-sulfobenzyl group, etc.) or aralkyl group (e.g. p-carboxybenzyl group, benzyl group, phenylethyl group, etc.). represent.

However, at least one of R and R2 is always a sulfoalkyl group or a carboxyalkyl group. X, is an anion (e.g., chloride ion, bromide ion,
(iodine ion, thiocyanate ion, sulfate ion, perchlorate ion, p-toluenesulfonate ion, methylsulfate ion, ethylsulfate ion, etc.). n represents an integer of 1 or 2, and when the dye forms an inner salt, n
=1. The oxacarbocyanine dye according to the present invention is represented by the following general formula ().

In the formula, B1, B2, B3, and B4 have the same meaning as A3 and A4, respectively.

RO is a hydrogen atom, a lower alkyl group (for example, a methyl group,
(ethyl group, etc.), aryl group (eg, phenyl group, etc.).

R3 and R4 have the same meaning as R1 and R2, respectively, and represent ★.

X2 represents the same meaning as X. m represents the same meaning as n and "O. Typical examples of benzimidazolo oxacarbocyanine dyes used in the present invention are listed below, but the sensitizing dyes used in the present invention are not limited by this. do not have.

Typical examples of oxacarbocyanine dyes used in the present invention are listed below, but these are not intended to limit the sensitizing dyes used in the present invention.

The dye represented by the general formula (1) is
Those skilled in the art can easily synthesize the sensitizing dyes described in No. 30, JP-A-47-33626, etc. by referring to the above specifications, and those not described can be synthesized by similar methods. The dye represented by the general formula () is U.S. Patent No. 3
No. 397060, British Patent No. 840223, French Patent No. 2
Those skilled in the art can easily synthesize the sensitizing dyes described in No. 182329 and the like by referring to the above specification, and those not described can be synthesized by similar methods.

The feature of the present invention is that the green region is sensitized by combining the sensitizing dye represented by the general formula (1) and the sensitizing dye represented by the general formula (2). The material is to give a small crossover.

This crossover largely depends on the ratio of the sensitizing dye represented by the general formula (1) and the sensitizing dye represented by the general formula ( Particularly low crossovers are obtained in the range where the molar ratio of sensitizing dye] is greater than about 4.

When green sensitization is performed only with the sensitizing dye represented by the general formula (1), as shown in Examples (described later), a relatively high crossover is obtained, but the sensitizing dye represented by the general formula () A low crossover can be obtained by using them together. Although commonly known anti-irradiation dyes are certainly useful in reducing crossover, they have the disadvantage of causing a decrease in sensitivity to light in the wavelength range that the dye absorbs.

However, when the sensitizing dye of the general formula () used in the present invention is incorporated into a silver halide emulsion, no decrease in sensitivity occurs even when the dye is contained at a relatively high concentration; It is characteristic that even sensitivity increases when used in combination with (1). This is probably because scattered light is prevented by light absorption on the surface of the silver halide grains to which the sensitizing dye of general formula () is adsorbed, whereas the anti-irradiation dye mainly dyes the binder in the silver halide emulsion. Therefore, it is thought that light absorption by the dye in the binder causes a decrease in sensitivity. Another feature of the present invention is that by using the combination of sensitizing dyes of the present invention, residual coloring caused by the dyes is small, sensitivity to light from a fluorescent intensifying screen is high, and X-ray photographic materials, etc. Safelight filter 1 (manufactured by Fujifilm.7) used in
A sufficiently safe spectral sensitivity distribution can be obtained in a safe light using an F67 filter.

Low crossover, which is one of the objects of the present invention, is achieved by using R3, R
This is obtained in the case of dyes in which both 4 are sulfoalkyl groups.

In the present invention, although various concentrations of individual sensitizing dyes can be used, it is advantageous to use about 1.0 x 10-5 to about 1.0 x 10-3 mol of sensitizing dye per gram mol of silver halide. It is.

In particular, about 4X1 of sensitizing dye per gram mole of silver halide.
Preference is given to using 0-5 to 1.6 x 10-4 mol. Usage ratio of dye combinations (molar ratio of dye represented by general formula (1)/dye represented by general formula ())
is preferably about 1/1 to about 1/10, particularly 1/4 to 1
/10 gives the most effective results.

The optimal concentration of sensitizing dye is determined according to methods known to those skilled in the art.
The sensitivity can be determined by dividing the same emulsion, allowing each part to contain a different concentration of sensitizing dye, and measuring the sensitivity.

The sensitizing dye is added to the emulsion by methods well known in this field.

These sensitizing dyes can also be directly dispersed in emulsions,
or first dissolved in a water-soluble solvent such as pyridine, methyl alcohol, ethyl alcohol, methyl cellosolve, acetone, etc. (or a mixture of such solvents), in some cases diluted with water, and in other cases only water. and can be added to emulsions in the form of these solutions.

It is also possible to apply ultrasonic vibration to this solution. Others, such as Special Publication No. 45-8231, Special Publication No. 44-23
No. 389, Special Publication No. 1977-27555, Special Publication No. 1977-2
No. 2948, German patent application (0LS) 1947935
No., U.S. Patent No. 3,485,634, U.S. Patent No. 3,34260
The method described in No. 5, US Pat. No. 2,912,343, etc. can also be used.

If desired, the sensitizing dyes can be dissolved separately in a suitable solvent and added separately to the emulsion, or the dyes can be dissolved in the same or a different solvent and added to the silver halide emulsion prior to addition. A method of mixing these solutions can also be used.

The emulsion containing the sensitizing dye is coated on a suitable support such as glass, cellulose derivative film, polyvinyl resin film (e.g. polystyrene film, polyvinyl chloride film, etc.), polyester film, synthetic paper, baryta paper, polyolefin coating. The dye must be uniformly distributed throughout the emulsion before coating, such as on covered photographic paper. These sensitizing dyes may be added to the emulsion at any time during the emulsion manufacturing process, but it is more convenient to add them after the second ripening is completed. The silver halide used in the emulsion of the present invention may be, for example, any one of silver chloride, silver bromide, silver iodide, silver chlorobromide, silver iodobromide, silver chloroiodobromide, etc. Silver oxide and silver chloroiodobromide are advantageous, and silver iodobromide is particularly preferred.

These silver halide grains are formed by a known method such as a single dinit method, a double dinit method or a controlled double dinit method. These photographic emulsions are part of the photographic process.
cPr0cess - Written by Mees, Mag Milan M
Published by acMillan, Photographic Chemistry 1"PhOtOgraphicChemi8try'
It is also described in books such as those written by Grafikide 8 and published by Faurtain Press, and is not known to those skilled in the art. It can be prepared by various methods such as the well-known ammonia method, neutral method, and acid method.

After such silver halide grains are formed, they can be washed with water to remove by-product water-soluble salts from the system, and then chemically ripened in the presence of a chemical sensitizer. In addition, it may be used as is without removing the water-soluble salts produced as by-products. These usages are described in the above book. The average diameter of the silver halide grains used (for example, measured by the projected area method or number average) is not particularly limited, but is preferably about 0.5 μm to about 2 μm.

In particular, about 0.7 μ to 1, 5 μ is preferable. The silver halide photographic emulsion used can be processed by commonly used chemical sensitization methods, such as gold sensitization (US Pat. No. 2,540,085, US Pat.
No. 97876, No. 2597915, No. 2399083
etc.): Sensitization with group metal ions, sulfur sensitization (U.S. Patent Nos. 1574944, 2278947, 24402)
No. 06, 2410689, 3189458, 3415649, etc.): reduction sensitization (US Pat. No. 2518698, 2419974, 29
No. 83610, etc.) or various combinations of these sensitization methods can be applied.

Polyoxyethylene derivatives (British Patent No. 981470,
It may also contain a sensitizer such as Japanese Patent Publication No. 31-6475, US Pat. No. 2,716,062, etc.), polyoxypropylene derivatives, and derivatives having a quaternary ammonium group.

The silver halide emulsion used is coated with a suitable antifoggant (
TifOgg&Nt) and stabilizers (8tabi11ze)
r).

For example, thiazolium salts, azaindenes, urazoles, sulfocatechols, oximes, mercaptotetrazoles, nitrones, nitrointazoles, polyvalent metal salts, thiouronium salts, and noble metal salts such as palladium, platinum, and gold can also be used. Furthermore, silver halide photographic milk used in the present invention. A developing agent such as hydroquinones, catechols, annobuenols, 3-
It is possible to contain pyrazolidones, ascorbic acid and its derivatives, reductones, phenylenediamines, etc., or a combination of two or more developing agents.

The developing agent may be contained in the silver halide emulsion and/or in other suitable layers in the photographic element. The developing agent may be added dissolved in a suitable solvent or in the form of a dispersion as described in US Pat. No. 2,592,368 and French Patent No. 1,505,778. The silver halide emulsions used may contain various organic or inorganic hardeners (e.g. formaldehyde,
chromalum, 1-hydroxy-3,5-dichlorotriazine soda, glyoxal, dichloroacrolein, etc.).

The silver halide photographic emulsion used in the present invention may also contain coating aids such as saponin, alkylaryl sulfonates and amphoteric compounds described in US Pat. No. 2,600,831 and the like. The silver halide photographic emulsion used in the present invention may also contain antistatic agents, plasticizers, fluorescent brighteners, development accelerators, air fog inhibitors, toning agents, color foggers, and the like. In addition, as a dye for preventing irradiation, for example, Japanese Patent Publication No. 41-20389, Japanese Patent Publication No. 41-20389,
3-3504, Japanese Patent Publication No. 43-13168, US Patent No. 2697037, US Patent No. 3423207, US Patent No. 28657
No. 52, British Patent No. 1030392, British Patent No. 1100546
It may also include those listed in the No.

In the present invention, conventional gelatin silver halide emulsions are used, but in place of gelatin, for example, albumin, agar, gum arabic, alginic acid, etc., or hydrophilic resins such as polyvinyl alcohol, polyvinylpyrrolidone, or photosensitive resins such as cellulose derivatives are used. Substances that do not have a deleterious effect on the silver halide may also be used.

The combination of dyes according to the present invention can be further used in combination with other sensitizing dyes.

In particular, the dye represented by the general formula [1] and/or the dye represented by the general formula [] and other dyes with supersensitizing action include methine dyes (for example, monomethine cyanine, monomethine cyanine,
Apomerocyanine (carbocyanine dye) is advantageously used. After exposure to radiation, the silver halide elements of this invention are preferably developed in a surface layer type developer.

In this case, high development activity is required in order for development to proceed rapidly, and this is achieved by adjusting the developer solution to an appropriate pH (for example, pH 9 to 12) by using a combination of a high-energy developer or a developer with superadditive action. Obtained by alkalization. The developer solution also contains customary additives such as sodium sulfite, hydroxylamine or its derivatives, hardeners, antifoggants such as benzotriazole, 5-nitrobenzimidazole, 5-nitrointazole, halides such as potassium bromide. , silver halide solvent, color toning agent, other dimethylformamide, dimethylacetamide,
N-methylpyrrolidone and the like may be included.

A radiation monochromatic dye image can also be obtained by a color development process as known from JP-A No. 48-55730.

On the other hand, as in the reversal color processing known from Japanese Patent Publication No. 40-23310, black and white development using metol or hydroquinone may be performed first, followed by processing to form a dye image. It is also possible to use the silver image in the form of a dye image plus a silver image without bleaching the silver image during the above processing steps. The silver halide photosensitive material for radiography of the present invention can be used not only for X-rays but also for β-rays,
It is also used to record penetrating radioactivity, including gamma radiation and fast electron beams, such as those obtained with electron microscopy.

Next, the present invention will be explained with reference to Examples, but these are for specifically explaining the present invention, and the present invention is not limited thereto.

Example 1 Silver iodobromide (AgI:AgBr=1.3 mol%; 98
．． 7 mol%; gelatin (v)/AgNO3 (r) = 0.
4:0.74 mol silver salt/Kg emulsion) An X-ray emulsion was prepared.

500 η/kg of emulsion as a stabilizer.
[Hydroxy-S-triazolo[1.5-a]pyrimidine was contained. This silver halide emulsion contained sensitizing dyes singly or in combination. The above emulsion was subbed on both sides and dyed blue (Bluetinte).
d) On both sides of the polyethylene terephthalate support, 3.57% silver per square meter on each side of the support.
The coating was applied to obtain a silver halide emulsion layer containing .

A protective layer of gelatin was applied over each emulsion layer at a coverage of 17 per square meter.

The coating was prepared using terbium-activated gadolinium oxysulfide (G) having the emission spectrum shown in FIG.
d2O2S) placed between fluorescent screens made of phosphor,
X
X-rays were irradiated with a tube voltage of 80K.

The exposed photographic element was processed using a roller conveyor processor according to the steps described below. The compositions of the developer and fixer are as follows. Developer (this developer has a pH value of about 10.30 at 20°C) Fixer (this fixer has a pH of about 4.20 at 20°C) obtained in Tables 1 and 2 The results of relative sensitivity and MTF value are shown.

Relative sensitivity is shown with the sensitivity when only the dye according to general formula (1) is used as 100 in each test. Also MTF
The value is a value at a spatial frequency of 1.5 lines/u. MTF
The higher the value, the better the sharpness. That is, it shows that the crossover is low. As shown in Table 1, the combination of sensitizing dyes used in the present invention (7163) is different from the combination of green-sensitive sensitizing dyes used in the comparative example (7165,
High sensitivity and high MTF compared to FU 8 and FU 10)
It is clear that a value is obtained.

Furthermore, as shown in Table 2, the combination of sensitizing dyes used in the present invention also provides high sensitivity and high MTF.
It is clear that a value is obtained.

[Brief explanation of the drawing]

FIG. 1 shows the spectral transmittance curve of a safe light filter commonly used for processing X-ray film.

Claims (1)

[Claims] 1. At least 1/1 of the energy of light emission due to radiation excitation.
2 is in a wavelength range exceeding 400 nm and the maximum emission is in the green region, and a silver halide photosensitive material having at least one silver halide photographic emulsion layer on a support is combined to produce radiation. A silver halide photographic light-sensitive material used in a method of obtaining a radiograph by developing the exposed light-sensitive material, wherein the silver halide light-sensitive material contains not more than 8.6 g of silver per square meter, and the halogen At least one of the silver oxide photographic emulsion layers is a combination of at least one sensitizing dye represented by the following general formula (I) and at least one sensitizing dye represented by the following general formula (II). A silver halide photosensitive material for radiography, characterized in that it contains: (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the formula, A_1 and A_
2 is a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, an acyloxyl group, an alkoxycarbonylamino group, a cyano group, a trifluoromethyl group, an alkoxycarbonyl group, an alkylsulfonyl group, a sulfamyl group, an alkylaminosulfonyl group, a morpholinosulfonyl group. , represents a morpholinocarbonyl group, piperidinosulfonyl group, carbamoyl group, or alkylcarbamoyl group, and A_3 and A_4 each represent a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a hydroxyl group, a phenyl group, a substituted phenyl group, or a carboxyl group. basis,
It represents an alkoxycarbonyl group, a cyano group, a trifluoromethyl group, an amino group, an acylamido group, an acyl group, an acyloxyl group, and an alkoxycarbonylamino group. B_1, B_2, B_3, B_4 are A_3, A respectively
Represents the same meaning as ＿4. R, R_1 and R_2 each represent an alkyl group or a substituted alkyl group commonly used in cyanine dyes. However, at least one of R_1 and R_2 shall be a sulfoalkyl group or a carboxyalkyl group. R_0 represents a hydrogen atom, a lower alkyl group or an aryl group. R_3 and R_4
represents the same meaning as R_1 and R_2, respectively. X_1 represents an anion. m and n each represent an integer of 1 or 2, and represent 1 when the dye forms an inner salt. X_2 represents an anion.