JP7621853B2 - Radiation detector - Google Patents

Description

An embodiment of the present invention relates to a radiation detector.

X-ray image detectors are becoming increasingly popular as X-ray imaging diagnostic equipment to replace X-ray film. Compared to X-ray film, X-ray image detectors have the advantages of a very short time from taking an X-ray to confirming the image, a wide dynamic range of images, and no need for chemicals required for film development.

The X-ray image detector comprises a photoelectric conversion substrate, a scintillator layer, etc. The photoelectric conversion substrate comprises a number of photoelectric conversion sections arranged in a matrix. In most X-ray image detectors currently in practical use, the scintillator layer converts the X-ray image that has passed through the human body into visible light, the photoelectric conversion section converts the converted visible light image into an electrical signal, and the photoelectric conversion section outputs image information created based on the converted electrical signal to the outside.

There are many types of scintillator layers that convert X-rays into light, but most current X-ray image detectors use one of two types of scintillator layers: oxide phosphors (Gd2O2S:Tb, etc.) and chlorides (CsI:Tl, etc.).

In particular, when using the chloride thallium-activated cesium iodide (CsI:TL), it is possible to form a scintillator layer by laying out multiple columnar crystals on a photoelectric conversion substrate and growing them vertically using the vacuum deposition method. Visible light generated inside the scintillator layer is trapped inside the columnar crystals, suppressing light scattering and enabling the production of high-resolution images.

In addition, by forming a reflective film mainly composed of a mixture of white pigment and resin on the surface of the scintillator layer, visible light that is generated inside the scintillator layer and escapes to the opposite side of the photoelectric conversion substrate can be reflected toward the scintillator layer. By increasing the amount of visible light that reaches the photoelectric conversion section of the photoelectric conversion substrate, a highly sensitive X-ray image detector can be obtained.

High-resolution X-ray images can be obtained by using a scintillator layer made of CsI, but the scintillator layer is highly hygroscopic, and when it is in contact with the atmosphere, it absorbs moisture from the air.

It is known that when a scintillator layer made of CsI:Tl absorbs moisture, the efficiency of converting X-rays into light in the scintillator layer decreases, and the absorption of moisture causes the columnar crystals to collapse, reducing the light trapping effect, resulting in a decrease in resolution and a decrease in the quality of the output X-ray image.

JP 2018-179510 A

This embodiment provides a radiation detector that can detect deterioration in radiation detection performance. Or, it provides a radiation detector that can suppress increases in product costs.

The radiation detector according to one embodiment includes:
a scintillator layer provided on the photoelectric conversion substrate and located at least in the detection region; a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer and adhered to the photoelectric conversion substrate; and a cover provided above the scintillator layer, located in the detection region and the non-detection region, adhered to the sealing portion, and covering the scintillator layer together with the photoelectric conversion substrate and the sealing portion, wherein a space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space reduced in pressure below atmospheric pressure, and the cover has a metal layer having a through hole located in the detection region, and a resin film laminated on the metal layer and air-tightly closing the through hole, wherein in a first state in which the space is reduced in pressure below atmospheric pressure, the cover is in close contact with the scintillator layer, and in a second state in which the air pressure inside the space is increased from the first state, the cover is separated from the scintillator layer.

Moreover, the radiation detector according to one embodiment includes:
The present invention comprises a photoelectric conversion substrate having a detection region and a non-detection region outside the detection region, a scintillator layer provided on the photoelectric conversion substrate and located at least in the detection region, a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer and adhered to the photoelectric conversion substrate, and a cover provided above the scintillator layer, located in the detection region and the non-detection region, adhered to the sealing portion, and covering the scintillator layer together with the photoelectric conversion substrate and the sealing portion, wherein the space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space reduced in pressure below atmospheric pressure, and the cover has a metal layer having recesses located in the detection region and the non-detection region.

FIG. 1 is a cross-sectional view showing an X-ray detector according to an embodiment. FIG. 2 is a perspective view showing a support substrate, an X-ray detection panel, a circuit board, a plurality of FPCs, and an image transmission section of the X-ray detector. FIG. 3 is a cross-sectional view showing a part of the X-ray detection panel. FIG. 4 is a plan view showing the X-ray detection panel. FIG. 5 is a cross-sectional view showing a part of the X-ray detection panel taken along line VV. FIG. 6 is a cross-sectional view showing a part of the X-ray detection panel, showing the X-ray detection panel in a normal state. FIG. 7 is a cross-sectional view showing a part of the X-ray detection panel, showing the X-ray detection panel in a state where a problem has occurred. FIG. 8 is a cross-sectional view showing a part of an X-ray detection panel according to a first modification of the above embodiment. FIG. 9 is a cross-sectional view showing a part of an X-ray detection panel according to a second modification of the above embodiment. FIG. 10 is a cross-sectional view showing a part of an X-ray detection panel according to a fourth modification of the above embodiment, showing a scintillator layer and a cover.

The following describes an embodiment of the present invention with reference to the drawings. Note that the disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive of while maintaining the gist of the invention are naturally included within the scope of the present invention. In addition, in order to make the explanation clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each figure, elements similar to those described above with respect to the previous figures are given the same reference numerals, and detailed explanations may be omitted as appropriate.

First, the basic concept of the embodiment of the present invention will be described.
In order to solve the problem of moisture absorption related to the scintillator layer, it is conceivable to cover the scintillator layer with a moisture-proof cover made of metal foil, and to bond the moisture-proof cover and the surface of the photoelectric conversion substrate at the periphery of the scintillator layer with a sealing part formed of an ultraviolet-curing adhesive, a thermoplastic resin, etc. This makes it possible to protect the scintillator layer from moisture contained in the external atmosphere and suppress deterioration of image quality generated by the X-ray image detector.

In addition, by reducing the pressure inside the space sealed by the moisture-proof cover, photoelectric conversion substrate, and sealing section, it is possible to remove even small amounts of moisture that may have been mixed in during manufacturing, suppressing deterioration of the scintillator layer due to moisture and suppressing deterioration of the image quality generated by the X-ray image detector.

As described above, the scintillator layer, which is easily deteriorated by moisture, is covered with a moisture-proof cover made of metal foil, and the moisture-proof cover and the photoelectric conversion substrate are bonded around the periphery of the scintillator layer to block moisture from the outside.

However, due to manufacturing issues, tiny leak paths can occur in the sealing section when the moisture-proof cover and photoelectric conversion substrate are bonded, which can allow the outside atmosphere to gradually infiltrate into the reduced pressure space. If the moisture in the infiltrating atmosphere causes the scintillator layer to deteriorate, the performance of the product can decrease, and the product can become unusable before its expected lifespan.

In addition, manufacturing problems may result in insufficient hardening of the sealing portion when bonding the moisture-proof cover to the photoelectric conversion substrate. This leads to a decrease in the adhesive strength between the moisture-proof cover and the photoelectric conversion substrate, and as a result, the moisture and thermal stresses that the product is subjected to during its use may cause the moisture-proof cover to peel off from the photoelectric conversion substrate. In this case, too, the outside atmosphere may gradually infiltrate into the reduced pressure space, and the moisture contained in the infiltrating atmosphere may cause the scintillator layer to deteriorate, reducing the performance of the product and causing problems with the use of the product before the expected product life.

It is difficult to completely prevent the above manufacturing problems with the current state of technology. Therefore, if it is possible to detect the intrusion of outside air into the reduced pressure space, the user can determine whether the scintillator layer has deteriorated. This makes it possible to encourage the user to repair or replace the product before it interferes with the use of the product, allowing the user to replace or repair the product in good time, minimizing problems caused by repairing or replacing the product.

A common means and method for detecting the intrusion of outside air into a reduced pressure space is to incorporate an air pressure sensor inside the reduced pressure space and use the air pressure sensor to detect the increase in internal pressure caused by the intrusion of gas into the reduced pressure space.

In the case of the above means and methods, since a moisture-proof cover is formed to cover the thin scintillator layer formed on the photoelectric conversion substrate, it is difficult to incorporate a thick air pressure sensor inside the reduced pressure space. In addition, it is also difficult to incorporate an air pressure sensor on top of the scintillator layer in the area where X-rays enter from the outside in order to avoid affecting the X-ray image.

For the reasons mentioned above, it is difficult to detect the intrusion of outside air into the reduced pressure space caused by a manufacturing problem. As a result, it is not possible to encourage repair or replacement of the product before performance degradation due to the intrusion of outside air occurs, and users do not notice until the degradation of product performance causes problems, resulting in major problems caused by replacement or repair only after the product is impaired in use.
Furthermore, incorporating an air pressure sensor into a product increases product costs, making it difficult to produce an inexpensive product.

To solve these problems, the embodiments of the present invention make it possible to detect the intrusion of outside air into the reduced pressure space, thereby minimizing problems during product use while keeping production costs down. The embodiments of the present invention make it possible to obtain a radiation detector that can detect deterioration in radiation detection performance. Or, it makes it possible to obtain a radiation detector that can prevent increases in production costs. Next, the means and methods for solving the above problems will be described.

(One embodiment)
First, an X-ray detector according to an embodiment will be described in detail.
1 is a cross-sectional view showing an X-ray detector 1 according to this embodiment. The X-ray detector 1 is an X-ray image detector, and is a flat panel X-ray detector that uses an X-ray detection panel.

As shown in FIG. 1, the X-ray detector 1 includes an X-ray detection module 10, a support substrate 12, a circuit substrate 11, spacers 9a, 9b, 9c, and 9d, a housing 51, an entrance window 52, and the like.
The X-ray detection module 10 includes an X-ray detection panel PNL, an FPC (flexible printed circuit board) 2e1, etc. The X-ray detection panel PNL is located between a support substrate 12 and an entrance window 52. The X-ray detection panel PNL includes a cover 7 facing the entrance window 52.

The entrance window 52 is attached to an opening of the housing 51. The entrance window 52 transmits X-rays. Therefore, the X-rays pass through the entrance window 52 and are incident on the X-ray detection panel PNL. The entrance window 52 is formed in a plate shape and has the function of protecting the inside of the housing 51. It is desirable to form the entrance window 52 thinly and using a material with low X-ray absorption rate. This makes it possible to reduce scattering of X-rays and attenuation of the amount of X-rays that occur at the entrance window 52. As a result, a thin and lightweight X-ray detector 1 can be realized.
The X-ray detection module 10 , the support substrate 12 , the circuit board 11 , etc. are housed inside a space surrounded by a housing 51 and an entrance window 52 .

The X-ray detection panel PNL is constructed by laminating thin members, so it is light and has low mechanical strength. For this reason, the X-ray detection panel PNL is fixed to one flat surface of the support substrate 12 via an adhesive sheet. The support substrate 12 is formed into a plate shape from, for example, an aluminum alloy, and has the strength required to stably hold the X-ray detection panel PNL. This makes it possible to prevent damage to the X-ray detection panel PNL when vibrations or impacts are applied to the X-ray detector 1 from the outside.

The circuit board 11 is fixed via spacers 9a and 9b to the other surface of the support board 12. By using the spacers 9a and 9b, it is possible to maintain an electrical insulation distance between the support board 12, which is mainly made of metal, and the circuit board 11.
The circuit board 11 is fixed to the inner surface of the housing 51 via spacers 9c and 9d. By using the spacers 9c and 9d, it is possible to maintain an electrical insulation distance between the housing 51, which is mainly made of metal, and the circuit board 11. The housing 51 supports the support substrate 12 and the like via the circuit board 11 and the spacers 9a, 9b, 9c, and 9d.

A connector corresponding to the FPC2e1 is mounted on the circuit board 11, and the FPC2e1 is electrically connected to the circuit board 11 via the connector. A thermocompression method using ACF (anisotropic conductive film) is used to connect the FPC2e1 to the X-ray detection panel PNL. This method ensures electrical connection between multiple fine pads on the X-ray detection panel PNL and multiple fine pads on the FPC2e1, and physically fixes the FPC2e1 to the X-ray detection panel PNL. The pads on the X-ray detection panel PNL will be described later.

As described above, the circuit board 11 is electrically connected to the X-ray detection panel PNL via the connector, FPC 2e1, etc. The circuit board 11 electrically drives the X-ray detection panel PNL and electrically processes the output signal from the X-ray detection panel PNL.

2 is a perspective view showing the support substrate 12, the X-ray detection panel PNL, the circuit board 11, the multiple FPCs 2e1 and 2e2, and the image transmission unit 4 of the X-ray detector 1. Note that not all components of the X-ray detector 1 are shown in FIG.
2, the X-ray detection panel PNL includes a photoelectric conversion substrate 2, a scintillator layer 5, etc. Incident X-rays 3 are absorbed inside the scintillator layer 5, and the scintillator layer 5 converts the incident X-rays 3 into fluorescence having a light intensity (brightness level) proportional to the intensity of the incident X-rays 3.

The photoelectric conversion substrate 2 has a substrate 2a, a plurality of photoelectric conversion units 2b, a plurality of control lines (or gate lines) 2c1, a plurality of data lines (or signal lines) 2c2, etc. Note that the number, arrangement, etc. of the photoelectric conversion units 2b, the control lines 2c1, and the data lines 2c2 are not limited to the example in FIG. 2.

The multiple control lines 2c1 extend in the row direction and are arranged at a predetermined interval in the column direction. The multiple data lines 2c2 extend in the column direction, intersect with the multiple control lines 2c1, and are arranged at a predetermined interval in the row direction.

Multiple photoelectric conversion units 2b are provided on one surface of the substrate 2a. The photoelectric conversion units 2b are provided in a rectangular area defined by a control line 2c1 and a data line 2c2. One photoelectric conversion unit 2b corresponds to one pixel of an X-ray image. The multiple photoelectric conversion units 2b are arranged in a matrix. For the above reasons, the photoelectric conversion substrate 2 is an array substrate.

Each photoelectric conversion unit 2b has a photoelectric conversion element 2b1 and a TFT (thin film transistor) 2b2 as a switching element. The TFT 2b2 is connected to a corresponding control line 2c1 and a corresponding data line 2c2. The photoelectric conversion element 2b1 is electrically connected to the TFT 2b2. The fluorescence converted inside the scintillator layer 5 reaches the surface of the photoelectric conversion substrate 2 installed adjacently and enters the photoelectric conversion element 2b1.

The control line 2c1 is electrically connected to the circuit board 11 via the FPC 2e1. The circuit board 11 provides a control signal S1 to the multiple control lines 2c1 via the FPC 2e1. The data line 2c2 is electrically connected to the circuit board 11 via the FPC 2e2. The photoelectric conversion element 2b1 converts the fluorescence into charge information. The image data signal S2 (charges stored in the photoelectric conversion unit 2b) converted by the photoelectric conversion element 2b1 is transmitted to the circuit board 11 via the TFT 2b2, the data line 2c2, and the FPC 2e2.

The X-ray detector 1 includes an image transmission unit 4. The image transmission unit 4 is connected to the circuit board 11 via wiring 4a. The image transmission unit 4 may be incorporated into the circuit board 11. The image transmission unit 4 generates an X-ray image based on image data signals that have been converted into digital signals by a number of analog-to-digital converters (not shown). The generated X-ray image data is output from the image transmission unit 4 to an external device.

FIG. 3 is a cross-sectional view showing a part of the X-ray detection panel PNL.
3, the photoelectric conversion substrate 2 includes a substrate 2a, a plurality of photoelectric conversion units 2b, and insulating layers 21, 22, 23, 24, and 25. The plurality of photoelectric conversion units 2b are located in a detection area DA. Each of the photoelectric conversion units 2b includes a photoelectric conversion element 2b1 and a TFT 2b2.

The TFT 2b2 has a gate electrode GE, a semiconductor layer SC, a source electrode SE, and a drain electrode DE. The photoelectric conversion element 2b1 is composed of a photodiode. Note that the photoelectric conversion element 2b1 may be configured to convert light into an electric charge.

The substrate 2a has a plate-like shape and is made of an insulating material. Examples of the insulating material include glass such as alkali-free glass. The planar shape of the substrate 2a is, for example, rectangular. The thickness of the substrate 2a is, for example, 0.7 mm. The insulating layer 21 is provided on the substrate 2a.

A gate electrode GE is formed on the insulating layer 21. The gate electrode GE is electrically connected to the control line 2c1. The insulating layer 22 is provided on the insulating layer 21 and the gate electrode GE. The semiconductor layer SC is provided on the insulating layer 22 and faces the gate electrode GE. The semiconductor layer SC is formed of a semiconductor material such as amorphous silicon as an amorphous semiconductor and polycrystalline silicon as a polycrystalline semiconductor.

A source electrode SE and a drain electrode DE are provided on the insulating layer 22 and the semiconductor layer SC. The gate electrode GE, the source electrode SE, the drain electrode DE, the control line 2c1, and the data line 2c2 are formed using a low-resistance metal such as aluminum or chromium.

The source electrode SE is electrically connected to the source region of the semiconductor layer SC. The source electrode SE is also electrically connected to the data line 2c2. The drain electrode DE is electrically connected to the drain region of the semiconductor layer SC.

The insulating layer 23 is provided on the insulating layer 22, the semiconductor layer SC, the source electrode SE, and the drain electrode DE. The photoelectric conversion element 2b1 is electrically connected to the drain electrode DE. The insulating layer 24 is provided on the insulating layer 23 and the photoelectric conversion element 2b1. The bias line BL is provided on the insulating layer 24 and is connected to the photoelectric conversion element 2b1 through a contact hole formed in the insulating layer 24. The insulating layer 25 is provided on the insulating layer 24 and the bias line BL.

The insulating layers 21, 22, 23, 24, and 25 are formed of insulating materials such as inorganic insulating materials and organic insulating materials. Examples of inorganic insulating materials include oxide insulating materials, nitride insulating materials, and oxynitride insulating materials. Examples of organic insulating materials include resins.

The scintillator layer 5 is provided on the photoelectric conversion substrate 2 (multiple photoelectric conversion sections 2b). The scintillator layer 5 is located at least in the detection area DA and covers the upper parts of the multiple photoelectric conversion sections 2b. The scintillator layer 5 is configured to convert incident X-rays into light (fluorescence).

The photoelectric conversion element 2b1 converts the light incident from the scintillator layer 5 into an electric charge. The converted electric charge is stored in the photoelectric conversion element 2b1. The TFT 2b2 can switch between storing electric charge in the photoelectric conversion element 2b1 and discharging electric charge from the photoelectric conversion element 2b1. If the self-capacity of the photoelectric conversion element 2b1 is insufficient, the photoelectric conversion substrate 2 may further have a capacitor (storage capacitor) and the electric charge converted by the photoelectric conversion element 2b1 may be stored in the capacitor.

The scintillator layer 5 is made of thallium-activated cesium iodide (CsI:Tl). If the scintillator layer 5 is formed using a vacuum deposition method, the scintillator layer 5 is made up of an aggregate of multiple columnar crystals. The thickness of the scintillator layer 5 is, for example, 600 μm. At the outermost surface of the scintillator layer 5, the thickness of the columnar crystals of the scintillator layer 5 is 8 to 12 μm.

The material forming the scintillator layer 5 is not limited to CsI:Tl. The scintillator layer 5 may be formed of thallium-activated sodium iodide (NaI:Tl), sodium-activated cesium iodide (CsI:Na), europium-activated cesium bromide (CsBr:Eu), sodium iodide (NaI), gadolinium oxysulfide (Gd ₂ O ₂ S), or the like.

When forming the scintillator layer 5 using the vacuum deposition method, a mask with an opening is used. In this case, the scintillator layer 5 is formed in the area facing the opening on the photoelectric conversion substrate 2. The scintillator material deposited by deposition is also deposited on the surface of the mask. The scintillator material is also deposited near the opening of the mask, and crystals grow so as to gradually protrude into the opening. When the crystals protrude from the mask into the opening, deposition of the scintillator material onto the photoelectric conversion substrate 2 near the opening is suppressed. Therefore, as shown in Figure 2, the thickness of the scintillator layer 5 near the periphery gradually decreases toward the outside.

Alternatively, the scintillator layer 5 may have a plurality of scintillator sections arranged in a matrix, each having a square prism shape, and provided in a one-to-one correspondence with the photoelectric conversion section 2b. When forming such a scintillator layer 5, a scintillator material in which gadolinium oxysulfide phosphor particles are mixed with a binder material is applied onto the photoelectric conversion substrate 2, and the scintillator material is baked and hardened. Thereafter, lattice-shaped grooves are formed in the scintillator material by dicing with a dicer, for example. In the above case, the space between the plurality of scintillator sections is set to a space reduced in pressure from atmospheric pressure.

The film-like cover 7 is provided above the scintillator layer 5 and covers the scintillator layer 5. The cover 7 completely covers the exposed portion of the scintillator layer 5. The cover 7 is in contact with the scintillator layer 5, etc.

Here, the distance between a pair of adjacent photoelectric conversion elements 2b1 is defined as the second length L2. The second length L2 is the linear length from the center of gravity of one photoelectric conversion element 2b1 to the center of gravity of the adjacent photoelectric conversion element 2b1 in a plan view.

Figure 4 is a plan view showing the X-ray detection panel PNL. In Figure 4, the scintillator layer 5 is marked with diagonal lines slanting upward to the right, and the sealing portion 8 is marked with diagonal lines slanting downward to the right. Figure 5 is a cross-sectional view showing a portion of the X-ray detection panel PNL along line V-V.

As shown in Figures 4 and 5, the photoelectric conversion substrate 2 has a detection area DA and a non-detection area outside the detection area DA. The detection area DA is a rectangular area. The non-detection area of the photoelectric conversion substrate 2 has a frame-shaped first non-detection area NDA1 located around the detection area DA, and a second non-detection area NDA2 outside the first non-detection area NDA1. In this embodiment, the second non-detection area NDA2 has a frame-like shape.

The scintillator layer 5 is located at least in the detection area DA. The scintillator layer 5 has a side surface 5a and an upper surface 5b. The side surface 5a is located in the first non-detection area NDA1. The side surface 5a is a forward tapered surface. The upper surface 5b of the scintillator layer 5 faces the cover 7.

The photoelectric conversion substrate 2 further includes a plurality of pads 2d1 and a plurality of pads 2d2. The pads 2d1 and 2d2 are located in a second non-detection area NDA2. In this embodiment, the plurality of pads 2d1 are arranged along the left side of the substrate 2a, and the plurality of pads 2d2 are arranged along the bottom side of the substrate 2a. For example, the pads 2d1 and 2d2 are provided on the insulating layer 23 and are not covered with the insulating layer 24 and the insulating layer 25.
Note that FIG. 4 shows a schematic representation of the multiple pads, and the number, shape, size, position, and pitch of the multiple pads are not limited to the example shown in FIG.

One control line 2c1 extends through the detection area DA, the first non-detection area NDA1, and the second non-detection area NDA2, and is electrically connected to one of the multiple pads 2d1. One data line 2c2 extends through the detection area DA, the first non-detection area NDA1, and the second non-detection area NDA2, and is electrically connected to one of the multiple pads 2d2.
One of the multiple wirings provided on the FPC 2e1 is electrically connected to one pad 2d1, and one of the multiple wirings provided on the FPC 2e2 is electrically connected to one pad 2d2 (Figure 2).

The X-ray detection panel PNL further includes a sealing portion 8. The sealing portion 8 is located in the first non-detection area NDA1 and surrounds the scintillator layer 5. The sealing portion 8 has a frame-like shape and extends continuously around the scintillator layer 5. The sealing portion 8 is adhered to the photoelectric conversion substrate 2 (e.g., the insulating layer 25).

The cover 7 is located in the detection area DA and the first non-detection area NDA1. In the plan view shown in FIG. 4, the cover 7 completely covers the scintillator layer 5. As shown in FIG. 5, the portion of the scintillator layer 5 that is not covered by the photoelectric conversion substrate 2 and the sealing portion 8 is completely covered by the cover 7. In other words, the cover 7 covers the scintillator layer 5 together with the photoelectric conversion substrate 2 and the sealing portion 8.

The cover 7 is directly bonded to the sealing portion 8. The cover 7 covers at least a portion of the sealing portion 8. For example, if the cover 7 and the sealing portion 8 are joined in an environment that is reduced in pressure below atmospheric pressure, the cover 7 can be brought into contact with the upper surface 5b of the scintillator layer 5, etc. The space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the cover 7 and in which the scintillator layer 5 is located is a space that is reduced in pressure below atmospheric pressure.

In addition, the scintillator layer 5 generally has voids that occupy about 10 to 40% of its volume. Therefore, if the voids contain gas, the gas may expand and damage the cover 7 when the X-ray detector 1 is transported by aircraft or used at high altitude. If the cover 7 and the sealing portion 8 are joined in an environment with a reduced pressure below atmospheric pressure, damage to the cover 7 can be suppressed even when the X-ray detector 1 is transported by aircraft. For these reasons, it is preferable that the pressure in the space defined by the photoelectric conversion substrate 2, the sealing portion 8, and the cover 7 is lower than atmospheric pressure.

The sealing portion 8 is formed of a material containing a thermoplastic resin. The sealing portion 8 is formed of a material containing a thermoplastic resin as a main component. The sealing portion 8 may be formed of 100% thermoplastic resin. Alternatively, the sealing portion 8 may be formed of a material in which an additive is mixed into a thermoplastic resin. If the sealing portion 8 contains a thermoplastic resin as a main component, the sealing portion 8 can bond the photoelectric conversion substrate 2 and the cover 7 by heating.

The thermoplastic resin may be nylon, PET (Polyethyleneterephthalate), polyurethane, polyester, polyvinyl chloride, ABS (Acrylonitrile Butadiene Styrene), acrylic, polystyrene, polyethylene, polypropylene, or the like. In this case, the water vapor permeability of polyethylene is 0.068 g·mm/day·m ² , and the water vapor permeability of polypropylene is 0.04 g·mm/day·m ^2. These water vapor permeabilities are low. Therefore, if the sealing portion 8 contains at least one of polyethylene and polypropylene as a main component, the amount of moisture that penetrates the inside of the sealing portion 8 and reaches the scintillator layer 5 can be significantly reduced.
The sealing portion 8 may be made of a material containing an ultraviolet-curable resin as a main component.

The cover 7 has a metal layer 31 and a resin film 32. The metal layer 31 is located in the detection area DA and the first non-detection area NDA1. The metal layer 31 is provided to prevent the characteristics of the scintillator layer 5 from deteriorating due to moisture contained in the atmosphere. The metal layer 31 is formed of a metal containing aluminum. The metal layer 31 may be formed of a metal containing copper, a metal containing magnesium, a metal containing tungsten, stainless steel, Kovar, etc. The cover 7 including the metal layer 31 functions as a moisture-proof cover and can prevent or significantly suppress the penetration of moisture.

The metal layer 31 may also function as a light reflecting layer. The light reflecting function of the metal layer 31 can increase the efficiency of light (fluorescence) utilization and improve the sensitivity characteristics. In other words, the metal layer 31 reflects light generated in the scintillator layer 5 that travels toward the side opposite to the side where the photoelectric conversion unit 2b is provided, so that the light travels toward the photoelectric conversion unit 2b.

The resin film 32 is laminated on the metal layer 31. The resin film 32 can be made of a material such as polyimide resin, epoxy resin, polyethylene terephthalate resin, Teflon (registered trademark), low-density polyethylene, high-density polyethylene, elastic rubber, etc. The metal layer 31 can contain, for example, the metals mentioned above. The metal layer 31 can be formed using a sputtering method, a lamination method, etc.

Next, the cover 7 of the X-ray detection panel PNL and the like will be described. Fig. 6 is a cross-sectional view showing a part of the X-ray detection panel PNL, and shows the X-ray detection panel PNL in a normal state.
4 and 6 , metal layer 31 has a thickness T. Metal layer 31 is preferably a metal foil having a thickness T of less than 100 μm. By making the space around scintillator layer 5 a reduced pressure space, cover 7 is pressed toward scintillator layer 5 by external atmospheric pressure, and cover 7 can be well adhered to scintillator layer 5.

The metal layer 31 is located between the scintillator layer 5 and the resin film 32. Since the metal layer 31 can be covered by the resin film 32, damage that may be caused to the metal layer 31 by external forces, etc. can be suppressed. Furthermore, if the metal layer 31 is provided closer to the scintillator layer 5 than the resin film 32, deterioration of the characteristics of the scintillator layer 5 due to moisture permeation through the resin film 32 can be suppressed.

The metal layer 31 has a through hole h. The through hole h is a high transmission area TA that has a relatively high radiation transmittance within the detection area DA. In this embodiment, the shape of the through hole h (high transmission area TA) is circular (perfect circle) in a plan view. However, the shape of the through hole h (high transmission area TA) may be a circle other than a perfect circle, such as an ellipse, a polygon such as a square, or another shape.

The resin film 32 airtightly closes the through-hole h of the metal layer 31. Because the through-hole h is completely blocked by the resin film 32, it is possible to prevent gas from entering the reduced pressure space from the outside through the through-hole h, and it is possible to suppress the intrusion of moisture. The space in which the scintillator layer 5 is located is maintained as a reduced pressure space.

In FIG. 6, when incident X-rays 3a at a certain angle enter from the outside into an area of the detection area DA other than the through-hole h, the incident X-rays 3a pass through the metal cover 7 and reach the scintillator layer 5. The incident X-rays 3a that reach the scintillator layer 5 are converted into fluorescent light 6a inside the scintillator layer 5, and the fluorescent light 6a propagates along the columnar structure of the scintillator layer 5 to reach the photoelectric conversion element 2b1. The fluorescent light 6a that reaches the photoelectric conversion element 2b1 is converted into an electrical signal by the photoelectric conversion element 2b1 and is output to the outside as an image signal.

On the other hand, the incident X-rays 3b pass through the through-holes h (high transmission areas TA) of the metal layer 31, are converted into fluorescent light 6b in the scintillator layer 5, are converted into an electrical signal by the photoelectric conversion element 2b1α, and are output to the outside as an electrical signal.

Comparing incident X-rays 3a and 3b, incident X-rays 3a and 3b have the same intensity when incident. However, while incident X-rays 3a are attenuated by metal layer 31 when passing through cover 7 (metal layer 31), incident X-rays 3b are not attenuated by metal layer 31 because they pass through through hole h.

As a result, the fluorescence 6b generated by the unattenuated incident X-rays 3b has a relatively high light intensity compared to the fluorescence 6a generated by the attenuated incident X-rays 3a. The signal output from the photoelectric conversion unit 2b (photoelectric conversion unit 2b having the photoelectric conversion element 2b1α) to which the fluorescence 6b is input is higher than the signal output from the photoelectric conversion unit 2b to which the fluorescence 6a is input.

In the detection area DA, the presence of through-hole h in the metal layer 31 results in different image output values even if the intensities of the incident X-rays 3a and 3b are the same, and displaying the output values as is as an image signal would result in a degradation of image quality. However, in a normal X-ray detection panel PNL, the photoelectric conversion element 2b1α into which the fluorescence generated by the incident X-rays 3b that have passed through the through-hole h is incident does not change.

Therefore, the attenuation of X-rays by the metal layer 31 is measured in advance, and the coefficient is multiplied by the signal value output from the photoelectric conversion unit 2b having the photoelectric conversion element 2b1α. When the intensity of the incident X-rays is uniform, the values of the image signals output from the multiple photoelectric conversion units 2b, including the photoelectric conversion unit 2b having the photoelectric conversion element 2b1α, become uniform, making it possible to prevent degradation of image quality.

In this embodiment, not only the metal layer 31 but also the resin film 32 is located in the detection area DA and the first non-detection area NDA1. In a plan view, the resin film 32 has the same shape and area as the metal layer 31, and completely overlaps the metal layer 31. In a plan view, the contour of the resin film 32 coincides with the contour of the metal layer 31.

Even if holes other than the through-holes h are undesirably formed in the metal layer 31 in the detection area DA or the first non-detection area NDA1, the resin film 32 can block all holes in the metal layer 31, and the space in which the scintillator layer 5 is located can be maintained as a reduced pressure space.

As shown in Figures 3 and 4, in a plan view, the maximum linear length in the high transmission area TA (through hole h) is defined as the first length L1. In this embodiment, the first length L1 is the diameter of the high transmission area TA (through hole h). It is preferable that the first length L1 is less than the second length L2.

When the first length L1 exceeds the second length L2, the range of the incident X-rays 3b passing through the through hole h becomes larger, the area in which the fluorescence 6b is generated based on the incident X-rays 3b expands, and the photoelectric conversion unit 2b receiving the fluorescence 6b spans multiple areas. The center position of the through hole h becomes unclear, and the difference between the image position of the incident X-rays 3b that have passed through the through hole h when the X-ray detection panel PNL is normal and the image position of the incident X-rays 3b that have passed through the through hole h when a leak path has occurred in the sealing unit 8 becomes unclear. For the above reasons, it is desirable that the first length L1 of the through hole h is smaller than the second length L2.

As shown in FIG. 4, the high transmission area TA (through hole h) is closer to the non-detection area NDA (first non-detection area NDA1) than the center of gravity CE of the detection area DA in a plan view. In other words, the third length L3 is less than the fourth length L4. Here, the third length L3 is the shortest distance from the through hole h to the first non-detection area NDA1, and the fourth length L4 is the shortest distance from the through hole h to the center of gravity CE. Compared to the case where L4<L3, the incidence angle of the X-ray emitted from the point light source is larger, so that when a leak path occurs in the sealing portion 8, the deviation width of the position of the fluorescence 6b generated in the scintillator layer 5 by the incident X-ray 3b transmitted through the through hole h can be relatively large. Therefore, it becomes easier to detect the occurrence of the leak path.
The X-ray detector 1 is configured as described above.

Next, we will explain the case where a problem occurs in the X-ray detection panel PNL, which is a product, due to a manufacturing problem. Figure 7 is a cross-sectional view showing a part of the X-ray detection panel PNL, and shows the X-ray detection panel PNL in a state where a problem has occurred.

As shown in FIG. 7, an abnormality exists in the sealing portion 8 due to a manufacturing problem, and a leak path 8p occurs inside the sealing portion 8 when the X-ray detector 1 is in use. When the leak path 8p occurs, outside air infiltrates through the leak path 8p into the space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the cover 7, which was previously depressurized. The infiltrating outside air increases the air pressure inside the space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the cover 7, and the pressure on the scintillator layer 5 side that the cover 7 receives due to atmospheric pressure decreases. Then, the cover 7 is released from its tight contact with the scintillator layer 5, and the cover 7 moves away from the scintillator layer 5 in the upward direction shown in FIG. 7, resulting in the creation of a gap G between the cover 7 and the scintillator layer 5.

If the X-ray detection panel PNL remains in the above-mentioned state, moisture contained in the outside air will gradually penetrate into the vicinity of the scintillator layer 5 through the leak path 8p, causing deterioration of the scintillator layer 5. Since this will cause deterioration in the performance of the X-ray detector 1 to detect X-rays, it is desirable for the X-ray detector 1 itself to be able to detect deterioration in its performance to detect X-rays.

In the X-ray detection panel PNL in the state shown in FIG. 7, when incident X-rays 3b at a certain angle pass through the through hole h and reach the scintillator layer 5, unlike FIG. 6, the fluorescence 6b based on the incident X-rays 3b is incident on another photoelectric conversion element 2b1β, not on the photoelectric conversion element 2b1α. This is because there is a gap G between the scintillator layer 5 and the cover 7, and the incident X-rays 3b at a certain angle pass through the space G, shifting the position at which they reach the scintillator layer 5, and shifting the relative positions of the fluorescence 6b generated by the incident X-rays 3b and the photoelectric conversion element 2b1α.

When the X-ray detection panel PNL is normal, fluorescence 6a based on incident X-rays 3a attenuated by the metal layer 31 is incident on the photoelectric conversion element 2b1β, but in FIG. 7, fluorescence 6b based on incident X-rays 3b that are not attenuated by the metal layer 31 is incident on the photoelectric conversion element 2b1β. The intensity of the fluorescence 6b incident on the photoelectric conversion element 2b1β is higher than the intensity of the fluorescence 6a in the normal state.

The image signal obtained by the incidence of fluorescence 6b based on incident X-rays 3b passing through through hole h on photoelectric conversion element 2b1β rises from the normal image signal. Therefore, by detecting an increase in the value of the image signal output from photoelectric conversion unit 2b having photoelectric conversion element 2b1β, it is possible to detect the occurrence of gap G in the X-ray detection panel PNL and to detect the presence of leak path 8p that causes gap G. Note that the above detection can also be performed by detecting a decrease in the value of the image signal output from photoelectric conversion unit 2b having photoelectric conversion element 2b1α.

According to the X-ray detector 1 according to one embodiment configured as described above, the X-ray detector 1 includes a photoelectric conversion substrate 2, a scintillator layer 5, a sealing portion 8, and a cover 7. The space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the cover 7, and in which the scintillator layer 5 is located, is a space whose pressure is reduced below atmospheric pressure. The cover 7 includes a metal layer 31 having a through hole h, and a resin film 32 laminated on the metal layer 31 and airtightly closing the through hole h.

The presence of the leak path 8p gradually deteriorates the performance of the scintillator layer 5. However, by using multiple photoelectric conversion units 2b and through holes h, it is possible to detect the relative positional deviation of the through holes h with respect to the photoelectric conversion substrate 2. It is then possible to easily detect the occurrence of the leak path 8p in the sealing unit 8. Therefore, by detecting the leak path 8p before the deterioration of the scintillator layer 5 due to the leak path 8p progresses, it is possible to detect an abnormality in the X-ray detector 1 before it interferes with the use of the X-ray detector 1. This allows the user time to take measures such as repairing or replacing the X-ray detector 1, minimizing the inconvenience to the user of the X-ray detector 1.

From the above, an X-ray detector 1 can be obtained that can detect deterioration in X-ray detection performance. In addition, the presence of a leak path 8p can be detected without providing a separate air pressure sensor inside the reduced pressure space. Therefore, an X-ray detector 1 can be obtained that can suppress increases in product costs.

(Variation 1)
Next, a first modification of the above embodiment will be described. The X-ray detector 1 has the same configuration as the above embodiment except for the configuration described in this first modification. Fig. 8 is a cross-sectional view showing a part of the X-ray detection panel PNL according to the first modification of the above embodiment.
As shown in FIG. 8 , the resin film 32 may be located between the scintillator layer 5 and the metal layer 31 .
The X-ray detector 1 according to the first modified example configured as above can also provide the same effects as those of the above-described embodiment.

(Variation 2)
Next, a second modification of the above embodiment will be described. The X-ray detector 1 has the same configuration as the above embodiment except for the configuration described in this second modification. Fig. 9 is a cross-sectional view showing a part of an X-ray detection panel PNL according to the second modification of the above embodiment.
9, the cover 7 may further include another resin film 33. The resin film 33 is laminated on the metal layer 31 and is located between the scintillator layer 5 and the metal layer 31. The resin film 33 also air-tightly closes the through hole h of the metal layer 31.

In the present modified example 2, the resin film 33 is located in the detection area DA and the first non-detection area NDA1. In a plan view, the resin film 33 has the same shape and area as the metal layer 31, and completely overlaps the metal layer 31. In a plan view, the outline of the resin film 33 coincides with the outline of the metal layer 31.
The X-ray detector 1 according to the second modified example configured as above can also provide the same effects as those of the above-described embodiment.

(Variation 3)
Next, a third modification of the above embodiment will be described. The above-described metal layer 31 may have a plurality of through holes h. The metal layer 31 has a plurality of through holes h located in the detection area DA, and each of the plurality of through holes h corresponds one-to-one to a high transmittance area TA.

The X-ray detector 1 according to the third modified example configured as above can also achieve the same effects as those of the above-mentioned embodiment. In addition, the relative positional deviation of the through-hole h with respect to the photoelectric conversion substrate 2 can be more easily detected.

(Variation 4)
Next, a fourth modification of the above embodiment will be described. Fig. 10 is a cross-sectional view showing a part of an X-ray detection panel PNL according to the fourth modification of the above embodiment, showing a scintillator layer 5 and a cover 7.

As shown in FIG. 10, the metal layer 31 may have a recess r corresponding to the high transmission region TA instead of the through hole h. The recess r does not penetrate the metal layer 31. The thickness Tr of the high transmission region TA of the metal layer 31 is less than the thickness T of the region of the metal layer 31 other than the high transmission region TA.

The recess r opens on the side opposite to the resin film 32, but may open on the resin film 32 side. In the fourth modification, too, the metal layer 31 can make the amount of X-ray absorption different between the high transmittance region TA and the detection region DA other than the high transmittance region TA. This makes it possible to detect the relative positional deviation of the recess r with respect to the photoelectric conversion substrate 2.
The X-ray detector 1 according to the fourth modified example configured as above can also provide the same effects as those of the above-described embodiment.

If there are no holes in the metal layer 31, it is possible to ensure the airtightness of the cover 7 with only the metal layer 31. Therefore, unlike the variant 4 in FIG. 10, the cover 7 may be configured without the resin film 32.

The metal layer 31 may also have multiple recesses r. The detection area DA has multiple high-transmittance areas TA. The cover 7 has multiple recesses r that correspond one-to-one to the multiple high-transmittance areas TA. In this case, the relative positional deviation of the recesses r with respect to the photoelectric conversion substrate 2 can be detected more easily.

Although the above embodiments of the present invention have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

For example, the techniques described in the above embodiment and the above modified examples are not limited to application to the X-ray detector 1, but may be applied to other X-ray detectors and various radiation detectors. The radiation detector may include a radiation detection panel that detects radiation, instead of the X-ray detection panel PNL .
The invention as originally claimed in the present application is set forth below.
[1] A photoelectric conversion substrate having a detection area and a non-detection area outside the detection area;
a scintillator layer provided on the photoelectric conversion substrate and positioned at least in the detection region;
a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer, and bonded to the photoelectric conversion substrate;
a cover that is provided above the scintillator layer, is located in the detection region and the non-detection region, is adhered to the sealing portion, and covers the scintillator layer together with the photoelectric conversion substrate and the sealing portion,
a space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space whose pressure is reduced below atmospheric pressure,
The cover is
a metal layer having a through hole located in the detection area;
A resin film laminated on the metal layer and airtightly closing the through hole.
Radiation detector.
[2] The metal layer has a plurality of through holes including the through hole and positioned in the detection region.
The radiation detector according to [1].
[3] The photoelectric conversion substrate further includes a plurality of photoelectric conversion units arranged in a matrix in the detection region,
Each of the photoelectric conversion units includes a switching element and a photoelectric conversion element electrically connected to the switching element,
In a plan view, the maximum linear length of the through hole is defined as a first length, and the distance between a pair of adjacent photoelectric conversion elements is defined as a second length,
The first length is less than the second length.
The radiation detector according to [1].
[4] The through hole is closer to the non-detection area than the center of gravity of the detection area in a plan view.
The radiation detector according to [1].
[5] A photoelectric conversion substrate having a detection area and a non-detection area outside the detection area;
a scintillator layer provided on the photoelectric conversion substrate and positioned at least in the detection region;
a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer, and bonded to the photoelectric conversion substrate;
a cover that is provided above the scintillator layer, is located in the detection region and the non-detection region, is adhered to the sealing portion, and covers the scintillator layer together with the photoelectric conversion substrate and the sealing portion,
a space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space whose pressure is reduced below atmospheric pressure,
the cover has a metal layer having a recess located in the detection area;
Radiation detector.
[6] The metal layer has a plurality of recesses including the recess and positioned in the detection region.
The radiation detector according to [5].
[7] The cover further has a resin film laminated on the metal layer.
The radiation detector according to [5].
[8] The photoelectric conversion substrate further includes a plurality of photoelectric conversion units arranged in a matrix in the detection region,
Each of the photoelectric conversion units includes a switching element and a photoelectric conversion element electrically connected to the switching element,
In a plan view, the maximum linear length of the recess is defined as a first length, and the distance between a pair of adjacent photoelectric conversion elements is defined as a second length.
The first length is less than the second length.
The radiation detector according to [5].
[9] The recess is closer to the non-detection area than the center of gravity of the detection area in a plan view.
The radiation detector according to [5].
[10] The metal layer is a metal foil having a thickness of less than 100 μm.
The radiation detector according to [1] or [5].
[11] The resin film is located in the detection area and the non-detection area,
The outline of the resin film coincides with the outline of the metal layer in a plan view.
The radiation detector according to [1] or [7].
[12] The metal layer is located between the scintillator layer and the resin film.
The radiation detector according to [1] or [7].
[13] The cover further has another resin film laminated on the metal layer and positioned between the scintillator layer and the metal layer.
The radiation detector according to [12].
[14] The resin film is located between the scintillator layer and the metal layer.
The radiation detector according to [1] or [7].

1...X-ray detector, PNL...X-ray detection panel, 2...photoelectric conversion substrate, 2a...substrate,
2b...photoelectric conversion unit, 2b1...photoelectric conversion element, 2b2...TFT, 5...scintillator layer,
8: sealing portion, 8p: leak path, 7: cover, 31: metal layer, h: through hole, r: recess TA: high transmittance area, 32: resin film, 33: resin film, 11: circuit board,
12: Support substrate; DA: Detection area; NDA, NDA1, NDA2: Non-detection area;
3, 3a, 3b... Incident X-ray, 6, 6a, 6b... Fluorescence, G... Gap, CE... Center of gravity, T... Thickness,
L1, L2...length.

Claims (14)

a photoelectric conversion substrate having a detection region and a non-detection region outside the detection region;
a scintillator layer provided on the photoelectric conversion substrate and positioned at least in the detection region;
a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer, and bonded to the photoelectric conversion substrate;
a cover that is provided above the scintillator layer, is located in the detection region and the non-detection region, is adhered to the sealing portion, and covers the scintillator layer together with the photoelectric conversion substrate and the sealing portion,
a space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space whose pressure is reduced below atmospheric pressure,
The cover is
a metal layer having a through hole located in the detection area;
a resin film laminated on the metal layer and airtightly closing the through hole ,
In a first state in which the space is decompressed below atmospheric pressure, the cover is in close contact with the scintillator layer,
In a second state in which the air pressure inside the space is increased from that in the first state, the cover is separated from the scintillator layer.
Radiation detector. The metal layer has a plurality of through holes including the through hole and positioned in the detection region.
The radiation detector according to claim 1 . the photoelectric conversion substrate further includes a plurality of photoelectric conversion units arranged in a matrix in the detection region,
Each of the photoelectric conversion units includes a switching element and a photoelectric conversion element electrically connected to the switching element,
In a plan view, the maximum linear length of the through hole is defined as a first length, and the distance between a pair of adjacent photoelectric conversion elements is defined as a second length,
The first length is less than the second length.
The radiation detector according to claim 1 . The through hole is closer to the non-detection area than the center of gravity of the detection area in a plan view.
The radiation detector according to claim 1 . a photoelectric conversion substrate having a detection region and a non-detection region outside the detection region;
a scintillator layer provided on the photoelectric conversion substrate and positioned at least in the detection region;
a frame-shaped sealing portion located in the non-detection region, surrounding the scintillator layer, and bonded to the photoelectric conversion substrate;
a cover that is provided above the scintillator layer, is located in the detection region and the non-detection region, is adhered to the sealing portion, and covers the scintillator layer together with the photoelectric conversion substrate and the sealing portion,
a space surrounded by the photoelectric conversion substrate, the sealing portion, and the cover and in which the scintillator layer is located is a space whose pressure is reduced below atmospheric pressure,
the cover has a metal layer having a recess located in the detection area;
Radiation detector. the metal layer has a plurality of recesses including the recess and located in the detection region;
The radiation detector according to claim 5 . The cover further includes a resin film laminated on the metal layer.
The radiation detector according to claim 5 . the photoelectric conversion substrate further includes a plurality of photoelectric conversion units arranged in a matrix in the detection region,
Each of the photoelectric conversion units includes a switching element and a photoelectric conversion element electrically connected to the switching element,
In a plan view, the maximum linear length of the recess is defined as a first length, and the distance between a pair of adjacent photoelectric conversion elements is defined as a second length.
The first length is less than the second length.
The radiation detector according to claim 5 . The recess is located closer to the non-detection area than the center of gravity of the detection area in a plan view.
The radiation detector according to claim 5 . The metal layer is a metal foil having a thickness of less than 100 μm.
The radiation detector according to claim 1 or 5. the resin film is located in the detection area and the non-detection area,
The outline of the resin film coincides with the outline of the metal layer in a plan view.
The radiation detector according to claim 1 or 7. The metal layer is located between the scintillator layer and the resin film.
The radiation detector according to claim 1 or 7. The cover further includes another resin film laminated on the metal layer and positioned between the scintillator layer and the metal layer.
The radiation detector of claim 12. The resin film is located between the scintillator layer and the metal layer.
The radiation detector according to claim 1 or 7.

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