JP2770207B2 - X-ray image reading method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reading an X-ray image from an X-ray photosensitive material.

[0002]

2. Description of the Related Art An imaging system for irradiating radiation transmitted through a subject to a radiation intensifying screen and an X-ray photosensitive material (X-ray film) disposed in close contact with the screen to take a radiation image of the subject is used for medical diagnosis. It is used in various fields such as medical radiography such as X-ray radiography and industrial radiography for nondestructive inspection of substances.

[0003] The radiation intensifying screen has, as a basic structure, a support and a phosphor layer provided on the surface thereof. The surface of the phosphor layer is generally provided with a protective layer made of a plastic film or the like. (Hereafter, this protective layer
Is also referred to as a protective film. ) Is provided. The X-ray film has a basic structure comprising a support and an emulsion layer provided on both sides of the support. An undercoat layer is provided between the support and the emulsion layer. Is the protective layer (hereinafter
Below, this protective layer is also called a protective film. ) Is provided.

It is desired that the film / screen photographing system has as high a sensitivity as possible in order to minimize the exposure dose to the subject. Further, it is desired that the obtained images have high image quality (sharpness, granularity, etc.). For this reason, a film / screen photographing system in which a radiographic intensifying screen is closely arranged on both sides of an X-ray film having an emulsion layer on both sides is used.

In such a film / screen photographing system, emitted light emitted from the intensifying screen is incident on an adjacent X-ray film. At this time, the emitted light is scattered in the intensifying screen, and further, the X-ray film. It also scatters when passing through each layer inside. The image is blurred due to the scattering of the emitted light. In addition to the absorption of the emitted light in each emulsion layer of the X-ray film, the emitted light may be absorbed by the emulsion layer on the opposite side after passing through the support of the X-ray film. In addition to being directly exposed by the fluorescent light from the intensifying screen, the light is also exposed by the fluorescent light from another intensifying screen, so-called crossover occurs. Since the crossover light spreads due to scattering and the like when transmitting through the emulsion layer of the film, the exposure of the photosensitive material by the crossover light causes deterioration in image quality (image blur). For these reasons, there has been a problem that the image quality on the conventional X-ray film tends to deteriorate.

[0006] Among these problems, the blurring of an image generated in the intensifying screen is caused by coloring the phosphor layer or the protective layer of the intensifying screen with a coloring agent, and scattering the emitted light in the intensifying screen by the coloring agent. It is known that it can be improved by absorption into the water (US Pat. No. 4,012,637, JP-A-54-107692). Japanese Patent Application Laid-Open No. 62-110199 discloses the use of a colorant having higher absorption at a wavelength longer than the peak of the emission wavelength in coloring the intensifying screen. It is also known that a support or an undercoat layer of an X-ray film is colored with a colorant absorbing light emitted from an intensifying screen to remove crossover light.

In recent years, X-ray films have been used not only as observation materials for visual observation, but also as detection materials for obtaining image signals by optically detecting them. That is, there is known a film image reading method in which a film on which an image is recorded is irradiated with reading light, reflected or transmitted light from the film is photoelectrically read, and the image is converted into a digital image signal. In this film image reading method, a film digitizer is used as an apparatus for performing the reading. In this method, a light beam such as a laser beam is scanned on a film, and light reflected or transmitted from the film is detected by a photodetector to obtain a time-series image signal. There are various types such as a type in which light from a film is sequentially read by a one-dimensional sensor such as a CCD line sensor arranged adjacent to the film. In any case, the digital image signal read from the film can be subjected to image processing by a computer or the like, whereby various processes such as gradation processing and frequency processing are performed, and the image signal after the image processing is displayed on a display unit. By displaying, a desired image can be observed.

[0008]

However, according to these conventional methods, it is impossible to prevent the spread of the emitted light emitted from the intensifying screen and the blurring of the image caused by the scattering of the emitted light inside the X-ray film. could not. As described above, simply applying the method of coloring with a colorant to an X-ray film makes it difficult to visually observe the X-ray film because it is a display material and an observation material at the same time as a detection material. I can not adopt it. For this reason, if a method of coloring the X-ray film to remove the crossover light is also adopted, this coloring is performed by the X-ray film.
The film must be decolorized in the process of developing, fixing, and washing the line film, and such a coloring is practically difficult and, at the same time, cannot be sufficiently colored.

In view of the above circumstances, the present invention solves the above-mentioned problems by using a film digitizer using an X-ray photosensitive material only as a detection material in combination with a colored X-ray photosensitive material. It is an object of the present invention to provide a method of reading an X-ray image having high sharpness.

[0010]

A first X-ray image reading method according to the present invention comprises a plurality of layers including at least a support, an emulsion layer and a protective layer, which are used in close contact with an intensifying screen; wherein a support, said emulsion layer and /
Or, the protective layer is hardly absorbed by the colorant by using a film digitizer on an X-ray photosensitive material on which X-ray image information is recorded by coloring the protective layer with a colorant that absorbs light emitted by the intensifying screen. Irradiate light of wavelength only ,
The X-ray image is read as a digital image signal by photoelectrically detecting light obtained from the X-ray photosensitive material by this irradiation.

A second X-ray image reading method according to the present invention comprises:
It consists of a plurality of layers including at least a support, an undercoat layer, an emulsion layer and a protective layer, which are used in close contact with an intensifying screen, wherein the support and / or the undercoat layer , the emulsion layer and / or Using a film digitizer on an X-ray photosensitive material recording X-ray image information obtained by coloring the protective layer with a coloring agent that absorbs light emitted from the intensifying screen, a wavelength that is hardly absorbed by the coloring agent is used. of
Irradiated with only light, by detecting light obtained from the X-ray sensitive material photoelectrically by the irradiation, and is characterized in that reading the X-ray image as a digital image signal.

In the X-ray image reading method of the present invention, for example, an X-ray photosensitive material having the following structure can be used.
FIGS. 1 to 3 are cross-sectional views each schematically showing a configuration example of an X-ray photosensitive material used in the X-ray image reading method of the present invention.

1) The emulsion layer 2 and the protective film 3 are
Has a configuration laminated on both sides in this order centering on
An X-ray photosensitive material in which one of the emulsion layer 2 and the protective film 3 (the protective film 3 in the figure) and the support 1 are colored with a coloring agent 5 (see FIG. 1).

2) The emulsion layer 2 and the protective film 3 are
Has a configuration laminated on both sides in this order centering on
An X-ray light-sensitive material in which the support 1, the emulsion layer 2 and the protective film 3 are colored by a coloring agent 5 (see FIG. 2).

[0015] 3) the undercoat layer 4 has the configuration emulsion layer 2 and the protective film 3 is laminated on both sides in this order around the support 1, of the Emulsion layer 2 and the protective film 3 of this At least one layer (protective film 3 in the figure), support 1 and undercoat
An X-ray sensitive material in which at least one of the layers 4 (undercoat layer 4 in the figure) is colored with a coloring agent 5 (see FIG. 3).

4) In the above 1) to 3), the emulsion layer and / or
Alternatively, when the protective layer is colored, a laminated structure having only one surface may be used.

In the above-mentioned X-ray light-sensitive material, the emulsion layer comprises a binder such as gelatin which contains silver halide in a dispersed state and the support comprises a plastic film such as polyethylene terephthalate. The protective film is a thin film layer coated with gelatin, and protects the emulsion layer from physical shock such as friction.

In the present invention, the colorant used to color the X-ray sensitive material has a spectral absorption characteristic of absorbing the emission light of the phosphor contained in the intensifying screen. Therefore, the colorant is selected according to the type of phosphor used in the intensifying screen.

The coloring agent used in the present invention is methylene blue, Victoria blue B, insulin, ultramarine, cobalt blue, navy blue or the like as a blue type, and Disperse Green 3B, malachite green, chrome green, cobalt green or oxidized as a green type. First light yellow G, oil yellow,
Chrome red G, disperse red R, oil red, thioisodigo maroon, and the like can be mentioned as red based on chrome yellow M, yellow lead, cadmium yellow, titanium yellow and the like. The coloring agent selected and used from the above coloring agents,
Before film formation of each layer of the X-ray photosensitive material, it is mixed and dispersed in a liquid precursor containing components constituting each layer. It is not necessary to decolor the coloring by these coloring agents during the development processing. Therefore, the colorant is not particularly limited, and various colorants can be used as long as they can be in each layer.

The intensifying screen used together with the X-ray sensitive material has a basic structure comprising a support and a phosphor layer provided thereon. The support can be arbitrarily selected from various materials known as materials for producing an intensifying screen, and a plastic film such as polyethylene terephthalate is preferred. The phosphor layer is made of a binder containing and supporting the phosphor. A protective film may be provided on the surface of the phosphor layer opposite to the surface in contact with the support for the purpose of physically and chemically protecting the phosphor layer.

Examples of the phosphor which emits light in the near ultraviolet to visible region (blue region, green region and red region) used in the present invention include the following compounds.

Tungstate phosphor (CaWO ₄ ,
MgWO ₄ , CaWO ₄ : Pb, etc.), terbium-activated rare earth oxysulfide phosphor [Y ₂ O ₂ S: Tb, Gd ₂ O ₂
S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O
₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, Tm, etc.],
Terbium-activated rare earth phosphate-based phosphor (YPO ₄ : T
b, GdPO ₄ : Tb, LaPO ₄ : Tb, etc.), terbium-activated rare earth oxyhalide phosphor (LaOB)
r: Tb, LaOBr: Tb, Tm, LaOCl: T
b, LaOCl: Tb, Tm, GdOBr: Tb, Gd
OCL: Tb, etc.), thulium-activated rare earth oxyhalide-based phosphors (LaOBr: Tm, LaOCl: Tm)
Etc.), barium sulfate-based phosphor [BaSO ₄ : Pb, Ba
SO ₄ : Eu ²⁺ , (Ba, Sr) SO ₄ : Eu ²⁺ etc.],
Divalent europium activated alkaline earth metal phosphate phosphor [Ba ₃ (PO ₄ ) ₂ : Eu ²⁺ , (Ba, Sr) ₃ (P
O ₄ ) ₂ : Eu ²⁺ etc., and divalent europium-activated alkaline earth metal fluorinated halide-based phosphor [BaFCl: Eu
²⁺ , BaFBr: Eu ²⁺ , BaFCl: Eu ²⁺ , Tb,
BaFBr: Eu ²⁺ , Tb, BaF ₂ .BaCl ₂ .K
Cl: Eu ²⁺ , BaF ₂ .BaCl ₂ .xBaSO _4.
KCl: Eu ²⁺ , (Ba, Mg) F ₂ .BaCl ₂ .K
Cl: Eu ²⁺ etc.], iodide-based phosphors (CsI: Na, C
sI: Tl, NaI, KI: Tl, etc.), sulfide-based phosphor [ZnS: Ag, (Zn, Cd) S: Ag, (Zn, C
d) S: Cu, (Zn, Cd) S: Cu, Al, etc.), hafnium phosphate-based phosphor (HfP ₂ O ₇ : Cu, etc.), europium-activated rare earth oxysulfide-based phosphor [Y ₂ O ₂ S : E
u, Gd ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, (Y,
Gd) ₂ O ₂ S: Eu, etc.], europium-activated rare earth oxide-based phosphor [Y ₂ O ₃ : Eu, Gd ₂ O ₃ : Eu, L
a ₂ O ₃ : Eu, (Y, Gd) ₂ O ₃ : Eu], europium-activated rare earth phosphate-based phosphor (YPO ₄ : Eu, G
dPO ₄ : Eu, LaPO ₄ : Eu, etc.), europium-activated rare earth vanadate-based phosphor [YVO ₄ : Eu, G
dVO ₄ : Eu, LaVO ₄ : Eu, (Y, Gd) VO
₄ : Eu].

However, the phosphor used in the present invention is not limited to these, but emits light emitted by the coloring agent of the colored layer in combination with the X-ray sensitive material. Any one may be used if it exists.

According to the X-ray image reading method of the present invention, a film digitizer is used on an X-ray photosensitive material on which the X-ray image information is recorded by using the imaging system configured as described above. By irradiating light having only a wavelength not absorbed and photoelectrically detecting transmitted light or reflected light obtained from the X-ray sensitive material by this irradiation,
This is a method of reading a line image as a digital image signal.

[0025]

In the X-ray photosensitive material used in the X-ray image reading method of the present invention, a colorant for absorbing light emitted from a phosphor contained in an intensifying screen using both a protective film and / or an emulsion layer. in so colored, oblique incident component as compared to the vertical incident component with respect to the X-ray sensitive material is relatively strength is weakened. Therefore, the intensity of the blurred component of the image is reduced, whereby an X-ray image with improved sharpness can be obtained.

Further, in the X-ray sensitive material, at least one of an undercoat layer and a support is colored with the coloring agent.
Since it is, it is possible to reduce the reflection at the undercoat layer or a support of the light-emitting light phosphors incident on the X-ray sensitive material, it is possible to improve the sharpness. Further, the emitted light can be prevented from transmitting through the support, and an image without crossover can be obtained.

Further, by using this X-ray light-sensitive material in combination with an intensifying screen in which a phosphor layer and / or a protective film is colored with the coloring agent, a sharper image can be obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings.

(Example) As a phosphor contained in the intensifying screen, an emission wavelength of 35 was used.
BaFCl: Eu, a divalent europium-activated alkaline earth metal fluorohalide-based phosphor having a wavelength of 0 to 450 nm
²⁺ was used. In the configuration of the X-ray photosensitive material shown in FIG. 1, the protective film 3 was colored with oil yellow of a yellow colorant 5 so as to have a transmittance of about 60% with respect to incident light. In the photographing system 7 shown in FIG. 4, intensifying screens 8a and 8b were pressed against the front and rear surfaces of the X-ray photosensitive material 9, respectively. X-rays were emitted from an X-ray generator 10 to a film / screen photographing system 7 through a subject 6, and a subject image was recorded on an X-ray photosensitive material 9. The X-ray photosensitive material 9 on which the visualized X-ray image information is recorded is applied to the X-ray photosensitive material 9 by using a film digitizer.
When a He-Ne laser having a wavelength of 2.8 nm was irradiated and the light obtained from the X-ray photosensitive material was detected by the irradiation, an X-ray image with high sharpness was obtained.

In the light-sensitive materials of the examples, the support was colored with the coloring agent so as to have a transmittance of about 10% with respect to incident light, without coloring the protective film with the coloring agent. This X-ray photosensitive material was arranged like the film screen photographing system shown in FIG. An X-ray generator 10 transmits an X-ray through a subject 6 to a film / screen photographing system 7
To record a subject image on the X-ray photosensitive material 9. The X-ray photosensitive material 9 on which the X-ray image information was recorded was irradiated with a He-Ne laser having a wavelength of 632.8 nm using a film digitizer, and the light obtained from the X-ray photosensitive material was detected by the irradiation. However, an X-ray image with high sharpness was obtained.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of an X-ray photosensitive material used in an X-ray image reading method of the present invention.

FIG. 2 is a sectional view showing the structure of an X-ray photosensitive material used in the X-ray image reading method of the present invention.

FIG. 3 is a sectional view showing the structure of an X-ray photosensitive material used in the X-ray image reading method of the present invention.

FIG. 4 is a schematic diagram for explaining X-ray image capturing in the X-ray image reading method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Support 2 Emulsion layer 3 Protective film 4 Undercoat layer 5 Colorant 7 Film / screen photographing system 8a, 8b intensifying screen 9 X-ray photosensitive material

Claims (2)

(57) [Claims] [Claim 1] used are arranged in close contact intensifying screen, at least the support consists of a plurality of layers including an emulsion layer and protective layer, and said support, and said emulsion layer and / or the protective layer, X on which X-ray image information recorded by coloring with a colorant absorbing the light emitted from the intensifying screen is recorded.
Line photosensitive material, using a film digitizer, the irradiating light of only the wavelength that is hardly absorbed in the coloring agent, by detecting light obtained from the X-ray sensitive material photoelectrically by the irradiation, the X An X-ray image reading method for reading a line image as a digital image signal. 2. A used are arranged in close contact intensifying screen comprises a plurality of layers including at least a support, a subbing layer, emulsion layer and protective layer, the support and / or pre <br/> SL under A coating layer , the emulsion layer and / or the protective layer ,
And the X-ray sensitive material for recording X-ray image information which is formed by coloring with a colorant which absorbs light emitted of the intensifying screen using a film digitizer, a light of a wavelength only that is hardly absorbed by the colorant An X-ray image reading method, wherein the X-ray image is read as a digital image signal by irradiating the light and photoelectrically detecting light obtained from the X-ray photosensitive material by the irradiation.