JP2021162506A - Scintillator panel, method for manufacturing scintillator panel, and radiation detector - Google Patents

Abstract

To provide a scintillator panel that can reduce the anisotropy of a coefficient of thermal expansion, a method for manufacturing a scintillator panel, and a radiation detector.SOLUTION: A scintillator panel is provided with a substrate, a scintillator layer that is provided on one side of the substrate and converts an incident radiation into fluorescent light, a reflection layer that is provided between the substrate and the scintillator layer and can reflect the fluorescent light generated in the scintillator layer, and a moisture-proof body that covers the scintillator layer. The substrate has one or more laminated sets of prepregs each composed of a first prepreg in which a plurality of carbon fibers are arranged in one direction and parallel to each other and a second prepreg in which a plurality of carbon fibers are arranged in a direction orthogonal to the first prepreg and parallel to each other.SELECTED DRAWING: Figure 4

Description

Embodiments of the present invention relate to scintillator panels, methods of manufacturing scintillator panels, and radiation detectors.

Radiation detectors with scintillator panels are known.
This type of radiation detector includes a scintillator panel having a scintillator layer formed on the substrate and an array substrate. The scintillator panel, for example, converts the received radiation into fluorescence which is visible light, and the array substrate has fluorescence. Is converted into an electric signal to detect radiation.

JP-A-2015-219208

Since the substrate of the scintillator panel needs to be able to efficiently transmit radiation and minimize the difference in thermal expansion from the scintillator layer, carbon fibers formed by laminating multiple layers of intermediate materials (hereinafter referred to as "prepregs") are formed. Reinforced plastic (CFRP) is used.
Generally, a prepreg in which carbon fibers are arranged in a predetermined direction has a different coefficient of thermal expansion depending on the arrangement direction. For example, the coefficient of thermal expansion is low in the direction along the arrangement direction of the carbon fibers, but the coefficient of thermal expansion is larger in the direction orthogonal to the arrangement direction of the carbon fibers than in the direction along the arrangement direction of the carbon fibers.

For this reason, a substrate manufactured using a plurality of prepregs may have anisotropy in the coefficient of thermal expansion of the entire substrate. If the coefficient of thermal expansion of the substrate is anisotropy, there may be restrictions in the process of attaching the scintillator panel to the array substrate, for example.

An object of the embodiment is to provide a scintillator panel capable of reducing the anisotropy of the coefficient of thermal expansion, a method for manufacturing the scintillator panel, and a radiation detector.

In one embodiment, a substrate, a scintillator layer provided on one side surface of the substrate and converting incident radiation into fluorescence, and a scintillator layer provided between the substrate and the scintillator layer to generate fluorescence generated in the scintillator layer. A reflective layer that can be reflected and a moisture-proof body that covers the scintillator layer are provided, and the substrate includes a first prepreg in which a plurality of carbon fibers are arranged in one direction and in parallel, and a plurality of prepregs with respect to the first prepreg. This is a scintillator panel in which one or more sets of prepregs composed of a second prepreg in which carbon fibers are arranged in orthogonal directions and in parallel are laminated.

One embodiment is a radiation detector including the scintillator panel and an array substrate provided on one side of the scintillator panel to convert fluorescence received from the scintillator layer into an electric signal.

One embodiment is composed of a first prepreg in which a plurality of carbon fibers are arranged in one direction and in parallel, and a second prepreg in which a plurality of carbon fibers are arranged in a direction orthogonal to the first prepreg and in parallel. This is a method for manufacturing a scintillator panel including a substrate on which one or more sets of prepregs are laminated, and a scintillator layer provided on one side surface of the substrate and converting incident radiation into fluorescence.

FIG. 1 is a schematic exploded perspective view showing a part of radiation detection according to an embodiment. FIG. 2 is a schematic cross-sectional view of radiation detection. FIG. 3 is a schematic cross-sectional view of the scintillator panel. FIG. 4 is an exploded perspective view of the substrate according to the first embodiment. FIG. 5 is an exploded perspective view of the substrate according to the second embodiment. FIG. 6 is an exploded perspective view of the substrate according to the third embodiment. FIG. 7 is an exploded perspective view of the substrate according to the fourth embodiment. FIG. 8 is an exploded perspective view of the substrate according to the comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention are naturally included in the scope of the present invention. Further, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment, but this is just an example, and the interpretation of the present invention is used. It is not limited. Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and detailed description thereof may be omitted as appropriate.

The radiation detector 1 according to the embodiment is a radiation detector that detects X-rays as radiation. The radiation detector 1 is an X-ray plane sensor that detects an X-ray image that is a radiation image, and is used, for example, for general medical applications. The use of the radiation detector 1 is not limited to general medical use, and can be used, for example, for non-destructive inspection.
As shown in FIGS. 1 and 2, the radiation detector 1 is provided with an array substrate 2, a signal processing unit 3, an image transmission unit 4, a scintillator panel 5, and a junction 6 (see FIG. 2). As shown in FIG. 1, the array substrate 2 has a substrate 2a, a photoelectric conversion unit 2b, a control line (or gate line) 2c1, and a data line (or signal line) 2c2.

The substrate 2a of the array substrate 2 has a plate shape and is formed of a translucent material such as non-alkali glass. A plurality of photoelectric conversion units 2b are provided on one surface of the substrate 2a. The photoelectric conversion unit 2b has a rectangular planar shape, and is provided in a region defined by the control line 2c1 and the data line 2c2.
The plurality of photoelectric conversion units 2b are arranged in a matrix. One photoelectric conversion unit 2b corresponds to one pixel. Each of the plurality of photoelectric conversion units 2b is provided with a photoelectric conversion element 2b1 and a thin film transistor (TFT) 2b2 which is a switching element.
The photoelectric conversion element 2b1 can be, for example, a photodiode or the like. The thin film transistor 2b2 switches the accumulation and emission of electric charges generated by the fluorescence incident on the photoelectric conversion element 2b1.
The thin film transistor 2b2 may include a semiconductor material such as amorphous silicon (a-Si) or polysilicon (P-Si). The thin film transistor 2b2 has a gate electrode, a source electrode, and a drain electrode. The gate electrode of the thin film transistor 2b2 is electrically connected to the corresponding control line 2c1. The source electrode of the thin film transistor 2b2 is electrically connected to the corresponding data line 2c2. The drain electrode of the thin film transistor 2b2 is electrically connected to the corresponding photoelectric conversion element 2b1 and a storage capacitor (not shown).

A plurality of control lines 2c1 are provided in parallel with each other at predetermined intervals. The control line 2c1 extends in the row direction, for example.
The plurality of control lines 2c1 are electrically connected to a plurality of wiring pads 2d1 provided in the vicinity of the peripheral edge of the substrate 2a. One ends of the plurality of wirings provided on the flexible printed substrate 2e1 are electrically connected to the plurality of wiring pads 2d1. The other ends of the plurality of wirings provided on the flexible printed board 2e1 are electrically connected to control circuits (not shown) provided on the signal processing unit 3, respectively.

A plurality of data lines 2c2 are provided in parallel with each other at predetermined intervals. The data line 2c2 extends, for example, in the column direction orthogonal to the row direction. The plurality of data lines 2c2 are electrically connected to each of the plurality of wiring pads 2d2 provided near the peripheral edge of the substrate 2a. One ends of the plurality of wirings provided on the flexible printed substrate 2e2 are electrically connected to the plurality of wiring pads 2d2. The signal processing unit 3 is provided on the side of the substrate 2a opposite to the side on which the photoelectric conversion unit 2b is provided.

The image transmission unit 4 is electrically connected to the amplification / conversion circuit of the signal processing unit 3 via the wiring 4a. The image transmission unit 4 may be integrated with the signal processing unit 3. The image transmission unit 4 constitutes an X-ray image based on an image data signal converted into a digital signal by a plurality of analog-digital converters. The configured X-ray image data is output from the image transmission unit 4 to an external device.

FIG. 3 is a cross-sectional view of the scintillator panel 5. As shown in FIGS. 2 and 3, the scintillator panel 5 is provided with a scintillator layer 7, a reflective layer 8A, a relaxation layer 8B, a substrate 9, and a moisture-proof body 10.
The scintillator layer 7 is provided on one surface of the substrate 9 via the reflective layer 8A. The scintillator layer 7 converts the incident X-rays into visible light, that is, fluorescence. The scintillator layer 7 can be formed using, for example, cesium iodide (CsI): thallium (Tl), sodium iodide (NaI): thallium (Tl), or the like. The thickness dimension of the scintillator layer 7 can be about 350 to 1000 μm. In this case, an aggregate of columnar crystals can be formed by using a vacuum vapor deposition method or the like.

The reflective layer 8A is provided on the side of the substrate 9 on which the scintillator layer 7 is provided. Further, the relaxation layer 8B is provided on the substrate 9 so that the rigidity is not concentrated in one direction on the side opposite to the side where the scintillator layer 7 is provided. As shown in FIG. 2, X-rays are incident from the side where the relaxation layer 8B is provided.
The reflective layer 8A is provided to increase the utilization efficiency of fluorescence and improve the sensitivity characteristics. That is, the reflection layer 8A reflects the light of the fluorescence generated in the scintillator layer 7 toward the side opposite to the side where the photoelectric conversion unit 2b is provided, and directs the light toward the photoelectric conversion unit 2b.
The reflective layer 8A and the relaxation layer 8B are composed of, for example, a reflective sheet made of foamed polyethylene terephthalate (foamed PET), a metal foil made of A1, Ag or the like, and a resin material (for example, polyethylene terephthalate (PET)). It can be formed of a reflective sheet or the like. The thickness of the reflective layer 8A and the relaxation layer 8B is about 190 μm in the case of the reflective sheet composed of foamed polyethylene terephthalate, and the thickness of the metal foil is 20 in the case of the reflective sheet composed of the metal foil and the resin material. The thickness of the resin layer can be about 50 μm to 50 μm, and the thickness of the resin layer can be 50 μm to 190 μm.

The joint portion 6 (see FIG. 2) is provided between the array substrate 2 and the scintillator panel 5.
The joining portion 6 has translucency and joins the array substrate 2 and the scintillator panel 5. The joint portion 6 may be formed by curing, for example, an optical double-sided tape (OCA tape (Optical Clear Adhesive Tape)), an optical adhesive, an optical gel, or the like. In this case, it can be cured by irradiation with ultraviolet rays.

FIG. 4 is an exploded perspective view of the substrate 9 of the scintillator panel 5.
The substrate 9 has a plate shape and is formed of carbon-fiber-reinforced plastic (CFRP) as a material having high X-ray transmittance. The substrate 9 is formed by laminating a plurality of layers of prepregs 11A, 11B, 12A, and 12B in which carbon fibers 9a are arranged in one direction and impregnated with a resin, and the prepregs 11A, 11B, 12A, and 12B are laminated and heat-treated under pressure to form a plate. Is.

In order to suppress the thermal expansion of the scintillator panel 5, it is preferable to select the substrate 9 having a low thermal expansion (coefficient of thermal expansion) and low anisotropy. Further, the cost of the substrate 9 depends on the number of layers of the prepregs 11A, 11B, 12A, and 12B, and it is preferable to reduce the number of layers of the carbon fiber reinforced plastic in order to reduce the cost.

In the first embodiment, an arbitrary direction of the substrate 9 is set to 0 ° (degrees), and the first prepreg 11A in which carbon fibers 9a are arranged and arranged in the direction of 0 ° is used as a reference with respect to the first prepreg 11A. The second prepreg 11B in which the carbon fibers 9a are arranged at an angle perpendicular to the direction of the carbon fibers 9a is set as the first set 11, and the direction of the carbon fibers 9a is 45 ° with respect to the reference 0 ° direction.
The first prepreg 12A in the direction and the second prepreg 12B in which the carbon fibers 9a are arranged in the direction of −45 ° in the direction of the carbon fibers 9a are set as the second group 12, and the upper and lower sides of the second group 12 (the thickness direction of the substrate 9). ) Are laminated with the first set 11 respectively. In this first embodiment, a total of three sets of two prepreg sets 11 and 12 whose carbon fiber directions are orthogonal to each other are laminated, and a total of six prepregs are laminated to form a substrate 9.

Here, if the substrate 9 is a molding method in which the substrate 9 is not arranged in the vertical direction with respect to the prepreg in an arbitrary direction, anisotropy of thermal expansion occurs. At this time, there is a possibility that restrictions may occur in the process of attaching the scintillator panel 5 to the array substrate 2. For example, when the substrate 9 is thermally expanded with anisotropy when left in a high temperature environment and then cooled and thermally shrunk, a space is created between the array substrate 2 and the scintillator panel 5 at the joint portion 6. On the contrary, the joint portion 6 may be aggregated, which may cause a defect in the image.
In the schematic view showing a comparative example in FIG. 8, three prepregs of the first prepreg 11A, the second prepreg 11B, and the first prepreg 11A are laminated in the plate thickness direction of the substrate 9, and the arbitrary direction of the substrate 9 is defined. When 0 °, the direction of the carbon fibers 9a is 0 ° for the first prepreg 11A and 90 ° for the second prepreg 11B. Moreover, when the thermal expansion of the substrate 9 was measured, it was found that there was a relationship of (coefficient of thermal expansion in the 90 ° direction)> (coefficient of thermal expansion in the 0 ° direction).
Carbon fiber reinforced plastic is known to have a low coefficient of thermal expansion, but it has a slight thermal expansion in the direction perpendicular to the fiber direction (direction of carbon fiber 9a), and it is a scintillator using CsI: Tl. It was found that the coefficient of thermal expansion in the 90 ° direction was extended in the form of being pulled by thermal expansion (coefficient of thermal expansion is generally 40 to 50 × 10 ^{-6 / ° C.).}

Therefore, with respect to the prepregs (layers) in which the directions of the carbon fibers of the substrate 9 are arranged in one direction, the prepregs (layers) having an angle in the vertical direction are made into one set (set), and a plurality of sets are stacked. The anisotropy of thermal expansion can be eliminated. For example, a set of prepregs 11B in which the carbon fibers 9a are arranged in the 90 ° direction is made into a set (first set 11) with respect to the prepreg 11A in which the direction of the carbon fibers 9a is arranged in an arbitrary reference angle of 0 °, and the carbon fibers 9a are formed. For the prepreg 12A arranged in the direction of 45 ° with respect to the arbitrary reference direction, the prepreg 12B arranged in the arrangement direction of the carbon fibers 9a in the direction of −45 ° is made into one set (second set 12). Laminate evenly with respect to the center in the plate thickness direction.
Here, in consideration of cost, it can be said that at least one set of carbon fiber layers (prepregs) is required, with two layers (prepregs) in which the directions of the carbon fibers 9a form 90 ° as one set.
By doing so, the anisotropy in the thermal expansion of the substrate 9 can be reduced, the thermal expansion of the scintillator panel 5 accompanying the scintillator layer 7 can be suppressed, and the restriction of the process of bonding the scintillator panel 5 to the array substrate 2 is reduced. However, stable quality can be obtained in consideration of cost merit.

As shown in FIGS. 2 and 3, the moisture-proof body 10 is provided to suppress deterioration of the characteristics of the scintillator layer 7 due to water vapor contained in the air. The moisture-proof body 10 is provided so as to cover the scintillator layer 7, the reflective layer 8A, the relaxation layer 8B, and the substrate 9.
The moisture-proof body 10 can be formed of a material having a light-transmitting property and a small moisture-permeable coefficient. The moisture-proof body 10 uses a moisture-proof film of an organic CVD film such as a polyparaxylylene resin, and penetrates into the gap portion of the scintillator layer 7 having a pillar structure to some extent. The organic CVD film has an advantage that it can be applied with a substantially uniform film thickness along the uneven structure accompanying the pillar structure.

The reflective layer 8A and the relaxation layer 8B contain polyethylene terephthalate, and in addition to polyparaxylylene in which the moisture-proof body 10 is formed by a thermal CVD method, polymonochloroparaxylylene, polyfluoroparaxylylene, polydimethylparaxylylene, When polydiethylparaxylylene or the like is contained, the portion of the surface where the reflective layer 8A and the relaxing layer 8B and the moisture-proof body 10 are in contact with each other has a high deterrent effect on the invasion of water. Therefore, the scintillator panel 5 having high moisture-proof performance can be obtained.

The effect of the first embodiment will be described.
As shown in FIG. 4, according to the first embodiment, the angle at which the direction of the carbon fibers 9a is perpendicular to the prepreg 11A (or 12A) in which the directions of the carbon fibers 9a of the substrate 9 are arranged in one direction. By forming one set of 11 (or 12) of the prepregs 11B (or 12B) and laminating one or more sets, the anisotropy of thermal expansion can be reduced. Here, in consideration of cost, at least one set is required and an even number of prepregs is required.

Since the substrate 9 is provided with a relaxation layer 8B capable of reflecting fluorescence on the surface opposite to the reflection layer 8A side, the utilization efficiency of fluorescence from the scintillator layer 7 toward the array substrate 2 is improved, and the sensitivity characteristics are improved. Can be improved.
Like the reflective layer 8A, the relaxation layer 8B is formed of a resin layer such as foamed PET bonded to the substrate 9, a metal layer such as Al or Ag connected to the resin layer, or a resin sheet such as PET. Therefore, it can be configured simply.

Other embodiments will be described below, but in the embodiments described below, parts that exhibit the same effects as those of the above-described embodiment are designated by the same reference numerals to give a detailed description of the parts. Is omitted, and the following description mainly describes the differences from one embodiment.
FIG. 5 shows an exploded perspective view of the substrate 9 according to the second embodiment. In the second embodiment, the prepreg 11A in which the carbon fibers 9a are arranged and arranged in the direction of 0 °, which is an arbitrary direction of the substrate 9, and the arrangement direction of the carbon fibers 9a is set to the vertical direction with respect to the prepreg 11A. The prepreg 11B is the first set, and the prepreg 12A in which the direction of the carbon fibers 9a is 45 ° and the prepreg 12B in which the direction of the carbon fibers 9a is −45 ° with respect to the reference 0 ° direction are the first set. As two sets, the first set is laminated on the second set in the plate thickness direction of the substrate 9. In this second embodiment, two sets of two prepregs whose carbon fiber directions are orthogonal to each other are formed by laminating a total of four prepregs. Other configurations are the same as those in the first embodiment.
According to this second embodiment, it is possible to obtain the same effects as those of the first embodiment described above.

FIG. 6 shows an exploded perspective view of the substrate 9 according to the third embodiment. In this third embodiment, the prepreg 12A in which the direction of the carbon fibers 9a is 45 ° and the prepreg 12B in which the direction of the carbon fibers 9a is −45 ° with respect to the reference direction of 0 ° are used as the first set. , Two sets of this first set are laminated one above the other in the plate thickness direction. In this second embodiment, two sets of two prepregs whose carbon fiber directions are orthogonal to each other are formed by laminating a total of four prepregs. Other configurations are the same as those in the first embodiment.
According to this third embodiment, it is possible to obtain the same effects as those of the first embodiment described above.

FIG. 7 shows an exploded perspective view of the substrate 9 according to the fourth embodiment. In the fourth embodiment, a prepreg 11A in which carbon fibers 9a are arranged in an arbitrary direction of the substrate 9 in a direction of 0 ° and an angle at which the direction of the carbon fibers 9a is perpendicular to the prepreg 11A. The prepreg 11B of the above is used as a set, and two sets of the prepreg 11B are laminated in the plate thickness direction of the substrate 9. In this second embodiment, two sets of two prepregs whose carbon fiber directions are orthogonal to each other are formed by laminating a total of four prepregs. Other configurations are the same as those in the first embodiment.
According to this fourth embodiment, it is possible to obtain the same effects as those of the first embodiment described above.

Although the above-described embodiment of the present invention has been described, the above-described embodiment is presented as an example and is not intended to limit the scope of the invention. The above-mentioned novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The above-described embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
For example, in the second embodiment shown in FIG. 5, two second sets of prepregs 12A and 12B may be provided in an overlapping manner, and a total of three sets may be configured to consist of six prepregs.
In the fourth embodiment shown in FIG. 7, three first sets of prepregs 11A and 11B may be stacked to form a total of three sets consisting of six prepregs, or four first sets may be stacked for a total of four. A set may consist of eight prepregs.

1 ... radiation detector, 2 ... array substrate, 5 ... scintillator panel, 7 ... scintillator layer, 8A ... reflective layer, 8B ... relaxation layer, 9 ... substrate, 11A, 11B, 12A, 12B ... prepreg, 11 ... 1st set , 12 ... 2nd group, 10 ... Moisture proof body.

Claims (5)

With the board
A scintillator layer provided on one side surface of the substrate and converting incident radiation into fluorescence,
A reflective layer provided between the substrate and the scintillator layer and capable of reflecting the fluorescence generated in the scintillator layer,
A moisture-proof body that covers the scintillator layer is provided.
The substrate is composed of a first prepreg in which a plurality of carbon fibers are arranged in one direction and in parallel, and a second prepreg in which a plurality of carbon fibers are arranged in a direction orthogonal to the first prepreg and in parallel. A scintillator panel in which one or more sets of prepregs are laminated. The scintillator panel according to claim 1, further provided with a relaxation layer made of the same material as the reflective layer, provided on the surface of the substrate opposite to the reflective layer side. The relaxation layer is a scintillator panel including a resin layer and a metal layer bonded to the substrate, or a resin sheet. A radiation detector comprising the scintillator panel according to any one of claims 1 to 3 and an array substrate provided on one surface side of the scintillator panel and converting fluorescence received from the scintillator layer into an electric signal. A set of prepregs composed of a first prepreg in which a plurality of carbon fibers are arranged in one direction and in parallel, and a second prepreg in which a plurality of carbon fibers are arranged in a direction orthogonal to the first prepreg and in parallel. With a substrate in which one or more sets are laminated,
A method for manufacturing a scintillator panel, comprising: a scintillator layer provided on one side surface of the substrate and converting incident radiation into fluorescence.

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