JP2003262672A - Radiation detection apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high sensitivity and low-cost radiation detection apparatus. <P>SOLUTION: The radiation detection apparatus is provided with at least a fluorescent material layer for converting radiation into light, an adhesive layer containing a fluorescent dye or a fluorescent pigment for absorbing the light emitted from the fluorescent material layer and emitting a light having a different wavelength and an optical detector, comprising a plurality of photoelectric conversion elements for converting the light with the converted wavelength into an electrical signal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detection apparatus and a method for manufacturing the same, and a radiation detection system, and more particularly to a radiation detection apparatus used for X-ray imaging and the like and a method for manufacturing the same.

In this specification, radiation includes light such as ultraviolet light, visible light and infrared light, and radiation such as X rays, α rays, β rays and γ rays.

[0003]

2. Description of the Related Art Conventionally, a radiation detecting apparatus comprising a radiation intensifying screen having a phosphor layer for converting X-rays into light and a radiation film having a photosensitive layer has been generally used for X-ray photography. However, recently, a digital radiation detecting device having a scintillator made of a phosphor layer and a two-dimensional photodetector made of a photoelectric conversion element has been developed. This digital radiation detection apparatus can easily perform image processing because the obtained data is digital data, and the data can be shared by loading it into a networked computer system, and the image digital data can be stored in a magneto-optical disk or the like. For example, the storage space can be significantly reduced compared to the case of storing the film, and there is an advantage that past images can be easily searched. In this case, in order to reduce the radiation dose to the patient, a digital radiation detector having high sensitivity and high sharpness is required.

For example, in Japanese Patent Laid-Open No. 7-27865, a photodetector is provided between two scintillators to improve the sensitivity of the digital radiation detecting apparatus.

Further, for example, Japanese Patent Laid-Open No. 11-344599.
Japanese Patent Laid-Open Publication No. 2003-242242 discloses an intensifying screen containing a fluorescent dye that absorbs light having a wavelength of 500 nm or less, which is emitted from a phosphor, converts it into light having a wavelength of 490 to 600 nm, and re-emits it. It is conceivable that a highly sensitive digital radiation detector can be obtained by bonding this intensifying screen to a two-dimensional photodetector with an adhesive.

[0006]

However, in Japanese Patent Laid-Open No. 7-27865, the sensitivity can be improved, but sufficient image sharpness cannot be obtained. The reason is that in order for the supporting substrate of the photodetector to have sufficient strength,
Since the fluorescence obtained from the scintillator on the back side of the photodetector passes through the supporting substrate and reaches the photodetector, the fluorescence must be diffused and diffused and the image sharpness must be increased. Is greatly deteriorated.

In JP-A-11-344599, the fluorescent dye is contained in the phosphor layer of the intensifying screen or the protective layer of the phosphor layer, but it is contained in the phosphor layer of the intensifying screen. When the fluorescent substance is present, the fluorescence emitted from the fluorescent substance near the protective layer of the fluorescent substance layer is not sufficiently captured by the fluorescent dye and is 500 nm.
Since the fluorescence of the following wavelengths is incident on the protective layer as it is, it is not possible to completely convert the wavelength of the light emitted from the phosphor,
It was not possible to improve the sensitivity to the maximum. Further, when contained in the protective layer of the phosphor layer, the light from the phosphor can be completely captured, converted in wavelength and incident on the photodetector, so that the sensitivity can be improved to the maximum extent. However, in this case, since the radiation detecting device cannot be used unless the adhesive layer is arranged between the protective layer and the photodetector, the sharpness is lowered due to the thickness of the adhesive layer.

[0008]

A radiation detecting apparatus of the present invention comprises at least a phosphor layer for converting radiation into light and a fluorescent dye for absorbing light emitted from the phosphor layer and emitting light of different wavelengths. Or an adhesive layer containing a fluorescent pigment,
And a photodetector including a plurality of photoelectric conversion elements that convert the wavelength-converted light into an electric signal.

Further, the photodetector is characterized by comprising a photoelectric conversion element using amorphous silicon.

Further, the above-mentioned fluorescent dye or pigment is 5
500 ~ 600nm by absorbing light with wavelength less than 00nm
It is characterized by re-emitting light of the wavelength.

The adhesive layer is composed of a fluorescent dye or fluorescent pigment and an adhesive or pressure-sensitive adhesive.

Further, the method for manufacturing a radiation detecting apparatus of the present invention is a light comprising a phosphor layer for converting radiation into light and a plurality of photoelectric conversion elements for converting the light converted by the phosphor layer into an electric signal. In the method of manufacturing a radiation detecting apparatus, which comprises a detector, an adhesive layer formed by bonding an adhesive or an adhesive containing a fluorescent dye or fluorescent pigment, which joins the phosphor layer and a photodetector, It is characterized in that the layer, the adhesive layer, and the photodetector are laminated by pressure molding in a batch with a roll.

That is, according to the present invention, the photoelectric conversion element made of amorphous silicon has a light absorption spectrum of 500 to 500.
Since it was found that the sensitivity was high at a wavelength of 600 nm, it absorbed between wavelengths shorter than 500 nm among the wavelengths of light emitted from the phosphor layer between the photoelectric conversion element and the phosphor layer, and 500 to 6
By bonding with an adhesive layer that has a light wavelength conversion function that converts light with a wavelength of 00 nm, it is possible to match the wavelength region with high light absorption sensitivity of the photoelectric conversion element, so that the light wavelength conversion efficiency is at a sufficient value. In addition, since the adhesive layer that joins the phosphor layer and the photodetector can have a light wavelength conversion function, the interval between the phosphor layer and the photodetector can be made extremely narrow, and the sharpness can be improved. The sensitivity can be significantly improved without lowering.

Further, as a method of manufacturing the radiation detecting apparatus of the present invention, the phosphor layer, the adhesive layer, and the photodetector are laminated by pressure-molding them together by a pressure roll. It can be manufactured at low cost.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a radiation detecting apparatus according to an embodiment of the present invention. FIG. 1 shows a photodetector 5 including 1-4.
FIG. 9 is a diagram in which a scintillator 10 composed of 7 and 9 is bonded via an adhesive layer 6 having a light wavelength conversion function. Figure 2
FIG. 3 is a diagram showing a method of manufacturing the scintillator of FIG. 1.

In FIG. 1, 1 is a substrate for a photodetector having an insulating property such as a glass substrate, 2 is a photoelectric conversion element using a semiconductor thin film made of amorphous silicon, and the photoelectric conversion element gap 3 has a photoelectric conversion element. A semiconductor element such as a TFT and a wiring for controlling the reading of charges from the photodetector are arranged, and 4 is a photodetector protective layer for protecting the semiconductor element inside the photodetector, and these constitute the photodetector 5. .

At this time, each photoelectric conversion element 2 has 10
They are arranged in a size of 0 to 200 μm square with a gap of about 20 to 60 μm.

Further, 7 is a phosphor layer containing phosphor particles for converting radiation into light, and 8 is provided as necessary,
A light reflection layer is provided when high sensitivity is required, and a light absorption layer is provided when high resolution is required. Further, reference numeral 9 denotes a phosphor support substrate of a phosphor layer and a light reflection layer, which form a scintillator 10.

The adhesive layer 6 is composed of a fluorescent dye or fluorescent pigment that absorbs light emitted from the phosphor layer and emits light of different wavelengths, and an adhesive or pressure-sensitive adhesive. The fluorescent pigment has an absorption spectrum peak in the range of 350 to 500 nm, and the emission spectrum peak needs to coincide with the absorption wavelength of 500 to 600 nm of the photoelectric conversion element made of amorphous silicon.

As such materials, known dyes or pigments, for example, "Handbook of Dyes" (edited by Organic Synthesis Society, 1970)
Annual), "Coloring Materials Engineering Handbook" (edited by Coloring Materials Association, 1
The dyes or pigments described in 1989) can be used. Particularly, as the material most suitable for the above wavelength range, a carbocyanine dye, a xanthene dye, a triarylylmethane dye, a coumarin dye, a phthalimide or a naphthalimide compound is desirable. .

As the above-mentioned adhesive, known transparent adhesives can be used. For example, polymers and / or copolymers of vinyl monomers such as vinyl acetate, ethylene, acrylic acid and acrylamide, polyamide, polyester, epoxy and the like. Thermoplastic adhesives, amino resins (urea resins, melamine resins), phenolic resins, epoxy resins, urethane resins, thermosetting adhesives such as thermosetting vinyl resins, natural rubber, nitrile rubber, chloro rubber, silicone rubber, etc. Examples include rubber adhesives. Especially hot melt adhesives,
For example, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, or a pressure-sensitive adhesive such as an acrylic-based, styrene-based, epoxy-based, or silicone-based pressure-sensitive adhesive is preferable because the manufacturing process can be simplified. The above-mentioned fluorescent dye or fluorescent pigment is heated and mixed with the above-mentioned adhesive as required to prepare the material for the adhesive layer of the present invention. An adhesive layer sheet for forming the adhesive layer of the present invention is formed by applying the above adhesive material in a sheet form with a thickness of 5 to 20 μm on release paper by a sheet forming apparatus such as a die coater and solidifying the adhesive material. Further, the main adhesive layer may be directly formed on the photodetector or the scintillator by the sheet forming apparatus. Although it varies depending on the fluorescent dye or fluorescent pigment used, the amount of the fluorescent dye or fluorescent pigment added to the phosphor is preferably approximately 0.001 wt% or more, and 0.5 wt% with respect to the adhesive resin to be mixed.
The following is preferable. 0.001w for phosphor
This is because if t% or less, a sufficient wavelength conversion amount cannot be obtained, and if it is 0.5 wt% or more with respect to the adhesive resin, compatibility with the resin is poor and light transmission is hindered, which is not preferable.

The phosphor layer 7 is made of, for example, CaWO ₄ , Gd ₂
A transparent resin is used as a binder for phosphor particles having a particle size of 1 to 20 μm, which are made of a phosphor material such as O ₂ S: Tb, BaSO ₄ : Pb, and the thickness varies depending on the phosphor material.
Approximately 50 to 500 μm to efficiently absorb radiation
Is set.

The light reflecting layer 8 can be formed by forming a thin metal film by a film forming method such as sputtering or vapor deposition, or by forming fine particles of a metal having a high refractive index, fine particles of a metal oxide such as silicon oxide, titanium oxide and aluminum oxide. It is formed by coating a material mixed with a transparent resin material as a binder on a phosphor support substrate. Alternatively, by mixing the above fine particles in a transparent resin and forming into a sheet, a phosphor support substrate which also serves as a light reflecting layer can be obtained.

The phosphor support substrate 9 may be made of any material and shape as long as it can protect the phosphor layer 7 and has a small X-ray absorption, but a resin film is preferable in view of ease of production. It may also serve as 8.

The scintillator is manufactured, for example, as follows. First, a transparent resin, a solvent and, if necessary, a dispersant are added to phosphor particles having a particle size of 1 to 20 μm made of a phosphor material.
An additive such as an antifoaming agent is added and mixed to prepare a phosphor coating solution. A sheet of this coating solution is formed on a phosphor support substrate 9 on which a light reflection layer 8 is formed in advance by using a coating method such as a doctor blade method to form a phosphor layer 7 having a predetermined thickness, and a scintillator 10 is manufactured. it can.

Further, a transparent resin film may be adhered on the phosphor layer, and a transparent resin thin film may be formed by vacuum film formation or the like to provide a phosphor protective layer.

The photodetector is manufactured by a known method, for example,
It can be prepared by the method disclosed in JP-A-9-145845.

As shown in FIG. 2, the photodetector 5 is arranged on the laminated stage 11, and the scintillator 10 is arranged.
It can be manufactured at a very low cost because it comprises a step of stacking by adhering to the adsorption table 12 and press-molding with the pressure roll 13 at once through the adhesive 6 through the adhesive 6.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) A method of manufacturing the radiation detecting apparatus shown in FIG. 1 will be described below.

A photoelectric conversion gap 3 composed of an amorphous silicon photoelectric conversion element 2 and an electric element such as a TFT is formed on a non-alkali glass substrate which is a photodetector substrate 1 having a thickness of 1.0 mm, and SiNx is formed on the photoelectric conversion gap 3. Semiconductor protective film 4
To form a photodetector 5.

The coating solution for the phosphor layer has an average particle size of 8 μm.
100 parts by weight of Gd ₂ O ₂ S: Tb, 3 parts by weight of ethyl cellulose, 20 parts by weight of terpineol, and 10 parts of xylene.
Parts by weight were mixed and dispersed by a sand mill to prepare a coating solution.

Next, using a doctor blade coater, the coating solution was applied onto a light-reflective phosphor supporting substrate 9 in which titanium oxide having a thickness of 250 μm was kneaded, and the weight after drying was 80 mg / cm ^2. And apply at 70 ℃, 5
The scintillator 10 was manufactured by performing the drying under the drying condition for a minute.

Next, 0.01 parts by weight of an organic fluorescent dye (Coumarin-6 manufactured by Aldrich Co.) was added to 100 parts by weight of a hot-melt type adhesive composed of an ethylene-acrylic acid copolymer and kneaded at 150 ° C. for 30 minutes. Then, the thickness of 10 μm on the polyethylene terephthalate film coated with the silicone resin release agent which is the release paper by the die coater.
Was applied to prepare a fluorescent dye-containing adhesive layer sheet.

Next, the photodetector 5 and the scintillator 10
While the release paper of the adhesive layer sheet was peeled off by the roll laminator shown in FIG. 2, the laminate was thermally laminated at 130 ° C. to prepare a radiation detecting device.

(Embodiment 2) A method of manufacturing another radiation detecting apparatus shown in FIG. 1 will be described below.

The photodetector 5 and the scintillator 10 are the first embodiment.
Was prepared in the same manner as in.

Next, a styrene hot melt adhesive, 1
0.01 parts by weight of an organic fluorescent dye (Coumarin-6 manufactured by Aldrich Co., Ltd.) was added to 00 parts by weight and kneaded at 120 ° C. for 30 minutes, and then a thickness of 10 μ was formed on the photodetector 5 by a die coater.
It was applied and formed by m.

Next, the photodetector 5 and the scintillator 10
A laminated radiation detection device was manufactured by using the roll laminator shown in FIG.

(Comparative Example 1) Photodetector 5 and scintillator 1
0 was produced in the same manner as in Example 1.

Next, a polyethylene terephthalate film coated with a silicone resin release agent, which is a release paper, was applied by a die coater in a thickness of 10 μm using only a hot-melt type adhesive consisting of an ethylene-acrylic acid copolymer, and was adhered. A layered sheet was prepared.

Next, the photodetector 5 and the scintillator 10
While the release paper of the adhesive layer sheet was peeled off by the roll laminator shown in FIG. 2, the laminate was thermally laminated at 130 ° C. to prepare a radiation detecting device.

(Comparative Example 2) The photodetector 5 was manufactured in the same manner as in Example 1.

The coating solution for the phosphor layer has an average particle size of 8 μm.
100 parts by weight of Gd ₂ O ₂ S: Tb, 3 parts by weight of ethyl cellulose, 20 parts by weight of terpineol, and 10 parts of xylene.
Parts by weight, organic fluorescent dye (manufactured by Aldrich: Coumarin-
0.003 parts by weight of 6) were mixed and dispersed by a sand mill to prepare a coating solution.

Next, using a doctor blade coater, the coating solution was applied onto a light-reflective phosphor supporting substrate 9 in which titanium oxide having a thickness of 250 μm was kneaded, and the weight after drying was 80 mg / cm ^2. And apply at 70 ℃, 5
Drying was carried out under the drying condition of minutes.

Then, a 6 μm thick polyethylene terephthalate film with a 5 μm thick acrylic hot melt adhesive was attached to one side to prepare a scintillator 10.

Then, a polyethylene terephthalate film coated with a silicone resin release agent, which is a release paper, was coated with a hot-melt type adhesive composed of an ethylene-acrylic acid copolymer by a die coater in a thickness of 10 μm to form an adhesive layer. A sheet was prepared.

Next, the photodetector 5 and the scintillator 10
While the release paper of the adhesive layer sheet was peeled off by the roll laminator shown in FIG. 2, the laminate was thermally laminated at 130 ° C. to prepare a radiation detecting device.

Table 1 shows the results of measuring the characteristics of the radiation detecting apparatus manufactured as described above. The sensitivity and the sharpness were taken with an X-ray with a tube voltage of 80 kvp through a water phantom of 10 cm.

The sharpness is CTF (value at 2 lp / mm according to Test Chart type 7 manufactured by Gokukosha Co., Ltd.), and Comparative Example 1 was set to 100.

[0052]

[Table 1]

From Table 1, as compared with Comparative Example 1, in Comparative Example 2, the sensitivity was improved because the fluorescent dye was mixed in the phosphor layer.
Sufficient sensitivity was not obtained as compared with Examples 1 and 2,
In No. 2, sharpness was not reduced, and a significant improvement in sensitivity was obtained.

[0054]

As described above, since the radiation detecting apparatus of the present invention can be matched with the wavelength region of the photoelectric conversion element having a high light absorption sensitivity, the light wavelength conversion efficiency can be obtained at a sufficiently required value. Since the adhesive layer for joining the phosphor layer and the photodetector can have a light wavelength conversion function, the distance between the phosphor layer and the photodetector can be made very narrow.
The sensitivity can be significantly improved without lowering the sharpness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a radiation detection apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram of a method for manufacturing the radiation detection apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1 Photodetector substrate 2 Photoelectric conversion element 3 Photoelectric conversion element gap 4 Photodetector protective layer 5 Photodetector 6 Adhesive layer 7 Phosphor layer 8 Light reflection layer 9 Phosphor layer support substrate 10 scintillator 11 Stacking stage 12 adsorption table 13 Pressure roll

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazumi Nagano             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Katsuro Takenaka             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2G088 FF02 FF04 FF05 FF06 GG16                       GG19 JJ05 JJ37                 5F088 AB05 BB03 BB07 EA04 EA08                       HA15 LA08

Claims (5)

[Claims] 1. A phosphor layer that converts radiation into light, an adhesive layer that contains a fluorescent dye or pigment that absorbs light emitted from the phosphor layer and emits light of different wavelengths, and a wavelength converter. And a photodetector including a plurality of photoelectric conversion elements for converting the converted light into an electric signal. 2. The radiation detecting apparatus according to claim 1, wherein the photodetector is a photoelectric conversion element using amorphous silicon. 3. The fluorescent dye or fluorescent pigment is 500.
The radiation detecting apparatus according to claim 1, wherein light having a wavelength of less than nm is absorbed and light having a wavelength of 500 to 600 nm is re-emitted. 4. The radiation detecting apparatus according to claim 1, wherein the adhesive layer is composed of a fluorescent dye or fluorescent pigment and an adhesive or an adhesive. 5. A phosphor layer for converting radiation into light, a photodetector comprising a plurality of photoelectric conversion elements for converting the light converted by the phosphor layer into an electric signal, the phosphor layer and light detection. In a method of manufacturing a radiation detecting apparatus, which comprises an adhesive layer composed of an adhesive or an adhesive containing a fluorescent dye or a fluorescent pigment, the fluorescent layer, the adhesive layer, and a photodetector are rolled. A method of manufacturing a radiation detecting device, comprising the steps of stacking by pressure molding in a batch according to.