阅读说明：本技术 放射线检测器及放射线图像摄影装置 (Radiation detector and radiographic imaging device ) 是由 牛仓信一 谷本达教 于 2020-04-24 设计创作，主要内容包括：本发明提供一种能够提高放射线图像的画质的放射线检测器及放射线图像摄影装置,所述放射线检测器具备：传感器基板,在挠性基材的像素区域形成对按照从放射线转换的光产生的电荷进行蓄积的多个像素；转换层,设置于基材的设置有像素区域的第1面上,并且将放射线转换为光；吸收层,设置于层叠有传感器基板和转换层的层叠体的与放射线所照射的一侧相反的一侧,并且吸收转换层中所产生的凹凸对传感器基板的影响；及刚性板,设置于吸收层的与对置于层叠体的一侧相反的一侧,并且比传感器基板刚性更高。(The invention provides a radiation detector and a radiographic imaging device capable of improving the quality of a radiographic image, the radiation detector including: a sensor substrate in which a plurality of pixels for accumulating charges generated in accordance with light converted from radiation are formed in a pixel region of a flexible base material; a conversion layer that is provided on the 1 st surface of the substrate on which the pixel region is provided, and that converts radiation into light; an absorption layer that is provided on the side of a laminate, on which the sensor substrate and the conversion layer are laminated, opposite to the side on which radiation is irradiated, and that absorbs the influence of irregularities generated in the conversion layer on the sensor substrate; and a rigid plate provided on the side of the absorption layer opposite to the side facing the laminate and having higher rigidity than the sensor substrate.)

1. A radiation detector is provided with:

a sensor substrate in which a plurality of pixels for accumulating charges generated in accordance with light converted from radiation are formed in a pixel region of a flexible base material;

a conversion layer that is provided on a surface of the substrate on which the pixel region is provided, and that converts the radiation into light;

an absorption layer that is provided on a side of a laminated body in which the sensor substrate and the conversion layer are laminated, the side being opposite to a side on which the radiation is irradiated, and that absorbs an influence of irregularities generated in the conversion layer on the sensor substrate; and

and a rigid plate provided on the side of the absorption layer opposite to the side opposite to the laminated body and having higher rigidity than the sensor substrate.

2. A radiographic imaging apparatus is provided with a radiation imaging device,

the radiation detector according to claim 1 is provided with a housing that houses the laminated body, the absorption layer, and the rigid plate in this order from a side to which radiation is irradiated.

3. The radiographic imaging apparatus according to claim 2,

the absorption layer has a durometer hardness lower than that of the entire laminate.

4. The radiographic imaging apparatus according to any one of claims 2 to 3,

the surface resistance value of the absorption layer is 10¹³Omega is less than or equal to.

5. The radiographic imaging apparatus according to any one of claims 2 to 4,

the radiographic imaging device further includes a reinforcing substrate that is provided between the absorption layer and the laminate and that disperses a compressive force applied to the absorption layer in an in-plane direction of the absorption layer.

6. The radiographic imaging apparatus according to any one of claims 2 to 4,

the radiographic imaging device further includes a reinforcing substrate that is provided on a side of the laminate opposite to the side of the absorption layer and that disperses a compressive force applied to the absorption layer in an in-plane direction of the absorption layer.

7. The radiographic imaging apparatus according to claim 5 or 6,

the reinforced substrate has a flexural modulus of 150MPa or more and 2500MPa or less.

8. The radiographic imaging apparatus according to any one of claims 5 to 7,

the flexural rigidity of the reinforced substrate is 540Pacm⁴Above 140000Pacm⁴The following.

9. The radiographic imaging apparatus according to any one of claims 2 to 8,

a radiation shielding layer for shielding the radiation is further provided between the absorption layer and the rigid plate.

10. The radiographic imaging apparatus according to any one of claims 2 to 9,

the rigid plate is a plate made of carbon.

11. The radiographic imaging apparatus according to any one of claims 2 to 10,

the laminate further includes a buffer material on a side of the laminate on which the radiation is incident.

12. The radiographic imaging apparatus according to any one of claims 2 to 11,

the conversion layer comprises columnar crystals of CsI.

13. The radiographic imaging apparatus according to any one of claims 2 to 12,

the radiographic imaging device further includes:

a control section that outputs a control signal for reading the electric charges accumulated in the plurality of pixels;

a driving section reading charges from the plurality of pixels according to the control signal; and

and a signal processing unit which receives an electric signal corresponding to the electric charge read from the plurality of pixels, generates image data corresponding to the received electric signal, and outputs the image data to the control unit.

Technical Field

The present invention relates to a radiation detector and a radiographic imaging device.

Background

Conventionally, there is known a radiographic imaging apparatus that performs radiography for the purpose of medical diagnosis. A radiation detector for detecting radiation transmitted through an object and generating a radiation image is used in such a radiation image capturing apparatus.

As the radiation detector, there is a radiation detector including: a conversion layer such as a scintillator that converts radiation into light; and a sensor substrate in which a plurality of pixels for accumulating electric charges generated by the light converted by the conversion layer are provided in the pixel region of the base material. As a base material of a sensor substrate of such a radiation detector, a base material using a flexible base material is known (for example, refer to japanese patent application laid-open No. 2013-217769). By using a flexible base material, for example, a radiation imaging apparatus (radiation detector) can be made lightweight, and it is sometimes easy to image a subject.

Disclosure of Invention

Technical problem to be solved by the invention

In a laminate or the like in which conversion layers are laminated on a sensor substrate, minute irregularities may occur. When a load or an impact is applied to the radiographic imaging device during radiography of a radiographic image, the irregularities generated in the laminate may propagate to the flexible base material, and the quality of the radiographic image generated by the radiation detector may be degraded.

The invention provides a radiation detector and a radiographic imaging device capable of improving the quality of radiographic images.

Means for solving the technical problem

A radiation detector according to claim 1 of the present invention includes: a sensor substrate in which a plurality of pixels for accumulating charges generated in accordance with light converted from radiation are formed in a pixel region of a flexible base material; a conversion layer that is provided on a surface of the substrate on which the pixel region is provided, and that converts radiation into light; an absorption layer that is provided on the side of a laminate, on which the sensor substrate and the conversion layer are laminated, opposite to the side on which radiation is irradiated, and that absorbs the influence of irregularities generated in the conversion layer on the sensor substrate; and a rigid plate provided on the side of the absorption layer opposite to the side facing the laminate and having higher rigidity than the sensor substrate.

A radiographic imaging device according to claim 2 of the present invention includes a housing that houses the radiation detector according to claim 1 in the order of a laminate, an absorption layer, and a rigid plate from a side to which radiation is irradiated.

A radiographic imaging device according to claim 3 of the present invention is the radiographic imaging device according to claim 2, wherein the absorption layer has a durometer hardness that is lower than the durometer hardness of the entire laminate.

A radiographic imaging device according to claim 4 of the present invention is the radiographic imaging device according to any one of claims 2 to 3, wherein the surface resistance value of the absorption layer is 10¹³Omega is less than or equal to.

A radiographic imaging device according to claim 5 of the present invention is the radiographic imaging device according to any one of claims 2 to 4, further comprising a reinforcing substrate that is provided between the absorbing layer and the layered body and that disperses a compressive force applied to the absorbing layer in an in-plane direction of the absorbing layer.

A 67-mode radiographic imaging device according to the present invention is the radiographic imaging device according to any one of modes 2 to 4, further comprising a reinforcing substrate that is provided on the side of the laminate opposite to the side of the absorption layer and that disperses a compressive force applied to the absorption layer in the in-plane direction of the absorption layer.

A radiographic imaging device according to claim 7 of the present invention is the radiographic imaging device according to claim 5 or 7, wherein the reinforcing substrate has a flexural modulus of elasticity of 150MPa to 2500 MPa.

A radiographic imaging device according to claim 8 of the present invention is any one of claims 5 to 7In the radiographic imaging apparatus of the embodiment, the flexural rigidity of the reinforcing substrate is 540Pacm⁴Above 140000Pacm⁴The following.

A radiographic imaging device according to claim 9 of the present invention is the radiographic imaging device according to any one of claims 2 to 8, further comprising a radiation shielding layer that shields radiation between the absorbing layer and the rigid plate.

A radiographic imaging device according to claim 10 of the present invention is the radiographic imaging device according to any one of claims 2 to 9, wherein the rigid plate is a plate made of carbon.

A radiographic imaging device according to claim 11 of the present invention is the radiographic imaging device according to any one of claims 2 to 10, further comprising a buffer material on the side of the laminate on which radiation is incident.

A radiographic imaging device according to claim 12 of the present invention is the radiographic imaging device according to any one of claims 2 to 11, wherein the conversion layer includes CsI columnar crystals.

A radiographic imaging device according to claim 13 of the present invention is the radiographic imaging device according to any one of claims 2 to 12, further comprising: a control section that outputs a control signal for reading the electric charges accumulated in the plurality of pixels; a driving section reading charges from the plurality of pixels in accordance with a control signal; and a signal processing unit which inputs electric signals corresponding to the electric charges read from the plurality of pixels, generates image data corresponding to the input electric signals, and outputs the image data to the control unit.

Effects of the invention

According to the present invention, the quality of a radiographic image can be improved.

Drawings

Fig. 1 is a structural diagram showing an example of a structure of a TFT (Thin film transistor) substrate in a radiation detector according to an embodiment.

Fig. 2 is a cross-sectional view for explaining an example of the base material of the embodiment.

Fig. 3 is a plan view of an example of the radiation detector of the PSS (transmission Side Sampling) system according to the embodiment as viewed from the Side irradiated with radiation.

Fig. 4 is a sectional view taken along line a-a of the radiation detector shown in fig. 3.

Fig. 5 is a cross-sectional view showing an example of the radiographic imaging device according to the embodiment.

Fig. 6 is a cross-sectional view for explaining the operation of the absorption layer in the radiation detector according to the embodiment.

Fig. 7 is a cross-sectional view showing another example of the radiographic imaging device according to the embodiment.

Fig. 8 is a cross-sectional view showing another example of the radiographic imaging device according to the embodiment.

Fig. 9 is a sectional view of another example of the radiation detector according to the embodiment.

Fig. 10 is a cross-sectional view showing an example of an ISS (Irradiation Side Sampling) type radiation detector according to the embodiment.

Fig. 11 is a cross-sectional view for explaining an influence of irregularities generated in the conversion layer on the sensor substrate in an example of the radiation detector (radiographic imaging device) of the comparative example.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present embodiment does not limit the present invention.

The radiation detector of the present embodiment has a function of detecting radiation transmitted through an object and outputting image information representing a radiographic image of the object. The radiation detector of the present embodiment includes a sensor substrate and a conversion layer that converts radiation into light (see the sensor substrate 12 and the conversion layer 14 of the radiation detector 10 in fig. 4).

First, an example of the structure of the sensor substrate 12 in the radiation detector according to the present embodiment will be described with reference to fig. 1. The sensor substrate 12 of the present embodiment is a substrate in which a plurality of pixels 30 are formed in the pixel region 35 of the base material 11.

The base material 11 is made of resin and has flexibility. The substrate 11 is, for example, a resin sheet made of plastic such as polyimide. The thickness of the base material 11 may be a thickness that can obtain desired flexibility depending on the hardness of the material, the size of the sensor substrate 12, and the like, and for example, when the base material 11 is a resin sheet, the thickness may be 5 to 125 μm, and more preferably 20 to 50 μm.

The substrate 11 has a characteristic of being able to withstand the manufacturing of the pixel 30, which will be described later in detail, and in the present embodiment, has a characteristic of being able to withstand the manufacturing of the amorphous silicon TFT (a-Si Thin Film Transistor). As the characteristics of the substrate 11, the thermal expansion coefficient at 300 to 400 ℃ is preferably about the same as that of an amorphous silicon (Si) wafer (for example,. + -. 5ppm/K), and more specifically, is preferably 20ppm/K or less. The heat shrinkage of the base material 11 is preferably 0.5% or less in the MD (Machine Direction) Direction at 400 ℃ in a thickness of 25 μm. The elastic modulus of the substrate 11 does not have a transition point that is common in polyimide in a temperature range of 300 to 400 ℃, and the elastic modulus at 500 ℃ is preferably 1GPa or more.

As shown in fig. 2, the substrate 11 of the present embodiment preferably has a fine particle layer 11L on the surface opposite to the side on which the conversion layer 14 is provided, in order to suppress backscattered radiation by itself, and the fine particle layer 11L includes inorganic fine particles 11P having an average particle diameter of 0.05 μm or more and 2.5 μm or less and absorbing backscattered radiation. When the resin substrate 11 is used as the inorganic fine particles 11P, it is preferable to use an inorganic substance having an atomic number of 30 or less and an atomic number larger than that of an organic substance constituting the substrate 11. Specific examples of the fine particles 11P include SiO, which is an oxide of Si having an atomic number of 14₂MgO, which is an oxide of Mg having an atomic number of 12, and Al, which is an oxide of Al having an atomic number of 13₂O₃And TiO, which is an oxide of Ti having an atomic number of 22₂And the like. A specific example of the resin sheet having such properties is XENOMAX (registered trademark).

In addition, the thickness in the present embodiment was measured using a micrometer (micrometer)And (4) degree. According to JIS K7197: 1991 the coefficient of thermal expansion was determined. In the measurement, test pieces were cut out from the main surface of the base material 11 at an angle of 15 degrees, and the thermal expansion coefficient of each cut out test piece was measured and the highest value was taken as the thermal expansion coefficient of the base material 11. The coefficient of thermal expansion was measured at intervals of 10 ℃ at-50 ℃ to 450 ℃ in the MD (machine Direction) Direction and TD (Transverse Direction), respectively, and (ppm/DEG C.) was converted to (ppm/K). For the measurement of the thermal expansion coefficient, the length of the sample was 10mm, the width of the sample was 2mm, and the initial load was 34.5g/mm using a TMA4000S machine manufactured by MAC Science corporation²The temperature rise rate was set to 5 ℃/min and the atmosphere was set to argon. According to JIS K7171: 2016, the modulus of elasticity is measured. In the measurement, test pieces were cut out from the main surface of the base material 11 at an angle of 15 degrees, and the cut test pieces were subjected to a tensile test to set the maximum value as the elastic modulus of the base material 11.

Each pixel 30 includes a sensor section 34 that generates and stores electric charges according to light converted by the conversion layer, and a switching element 32 that reads the electric charges stored by the sensor section 34. In the present embodiment, a Thin Film Transistor (TFT) is used as the switching element 32, for example. Therefore, the switching element 32 is hereinafter referred to as "TFT 32".

The plurality of pixels 30 are two-dimensionally arranged in one direction (a scanning wiring direction corresponding to the horizontal direction in fig. 1, hereinafter also referred to as a "row direction") and an intersecting direction (a signal wiring direction corresponding to the vertical direction in fig. 1, hereinafter also referred to as a "column direction") intersecting the row direction on the pixel region 35 of the sensor substrate 12. In fig. 1, the arrangement of the pixels 30 is simplified, and for example, 1024 × 1024 pixels 30 are arranged in the row direction and the column direction.

The radiation detector 10 is provided with a plurality of scanning lines 38 and a plurality of signal lines 36, the scanning lines 38 controlling the switching states (on and off) of the TFTs 32, and the signal lines 36 being present in each column of the pixels 30 and reading the charges accumulated in the sensor sections 34, respectively. Each of the plurality of scanning lines 38 is connected to a driving section 103 (see fig. 5) outside the radiation detector 10 via a pad (not shown) provided on the sensor substrate 12, and a control signal for controlling the switching state of the TFT32 output from the driving section 103 is passed therethrough. Each of the plurality of signal wirings 36 is connected to a signal processing section 104 (see fig. 5) outside the radiation detector 10 via a pad (not shown) provided on the sensor substrate 12, and outputs the electric charges read from each pixel 30 to the signal processing section 104.

In the sensor unit 34 of each pixel 30, a common wiring 39 is provided in the wiring direction of the signal wiring 36 in order to apply a bias voltage to each pixel 30. The common wiring 39 is connected to a bias power supply outside the radiation detector 10 via a pad (not shown) provided on the sensor substrate 12, and a bias is applied to each pixel 30 from the bias power supply.

The radiographic imaging device 1 including the radiation detector 10 of the present embodiment will be described in further detail with reference to fig. 3 to 5. The radiation detector 10 of the present embodiment is an iss (irradiation Side sampling) type radiation detector that includes a laminated body 19 in which conversion layers 14 are formed on a sensor substrate 12 and that is irradiated with radiation R from the sensor substrate 12 Side. Fig. 3 is a plan view of an example of the radiographic imaging device 1 including the radiation detector 10 of the present embodiment, as viewed from the side on which the sensor substrate 12 is formed. In other words, fig. 3 is a plan view of the radiographic imaging device 1 (radiation detector 10) viewed from the side irradiated with the radiation R. Fig. 4 is a cross-sectional view taken along line a-a of the radiation detector 10 in fig. 3. Fig. 5 is a cross-sectional view of an example of the radiographic imaging device 1 in which the radiation detector 10 shown in fig. 3 and 4 is housed in the housing 120.

Hereinafter, the structure of the radiation detector 10 is referred to as "upper" and is shown to be located above in the positional relationship with reference to the sensor substrate 12 side in fig. 4. For example, the conversion layer 14 is disposed above the sensor substrate 12.

As shown in fig. 3 to 5, the radiographic imaging device 1 of the present embodiment includes a protective layer 62, an antistatic layer 60, a sensor substrate 12, a conversion layer 14, a reinforcing substrate 50, an absorption layer 52, a radiation shielding layer 54, and a rigid plate 56. As shown in fig. 5, the radiographic imaging device 1 is housed in the housing 120 in a state in which the protective layer 62, the antistatic layer 60, the sensor substrate 12, the conversion layer 14, the reinforcing substrate 50, the absorption layer 52, the radiation shielding layer 54, and the rigid plate 56 are formed in this order from the side irradiated with the radiation R.

As shown in fig. 3 to 5, the conversion layer 14 of the present embodiment is provided on a region including a part of the pixel region 35 on the 1 st surface 11A of the base material 11 in the sensor substrate 12. As described above, the conversion layer 14 of the present embodiment is not provided on the region of the outer peripheral portion of the 1 st surface 11A of the substrate 11.

In the present embodiment, a scintillator including CsI (cesium iodide) is used as an example of the conversion layer 14. Such a scintillator preferably includes, for example, a CsI: t1 (cesium iodide with thallium added) or CsI: na (cesium iodide with sodium added). In addition, CsI: the emission peak wavelength in the visible light region of T1 was 565 nm.

As an example shown in fig. 4, in the radiation detector 10 of the present embodiment, the conversion layer 14 is formed directly as a stripe-shaped columnar crystal (not shown) on the sensor substrate 12 by a Vapor Deposition method such as a vacuum Deposition method, a sputtering method, or a CVD (Chemical Vapor Deposition) method. Examples of the method for forming conversion layer 14 include a vacuum deposition method using CsI: when T1 is the conversion layer 14, CsI: t1 is heated to be vaporized, and the temperature of the sensor substrate 12 is set to room temperature (20 ℃) to 300 ℃ to adjust CsI: t1 is deposited on the sensor substrate 12. The thickness of the conversion layer 14 is preferably 100 μm to 800 μm.

In the present embodiment, the end portion of the columnar crystal of the conversion layer 14 on the base point side in the growth direction (the sensor substrate 12 side in the present embodiment) is referred to as a "root portion", and the tip portion on the opposite side to the root portion in the growth direction is referred to as a "tip end". A buffer layer (not shown) is preferably provided between the sensor substrate 12 and the conversion layer 14. As the buffer layer in this case, a PI (PolyImide) film or a parylene (registered trademark) film may be used.

As shown in fig. 3 and 4, the radiation detector 10 of the present embodiment includes an adhesive layer 40, a reflective layer 42, an adhesive layer 44, and a protective layer 46. In the following, the arrangement direction (vertical direction in fig. 4) of the sensor substrate 12 and the conversion layer 14 is referred to as a stacking direction (refer to a stacking direction P in fig. 4).

As an example, as shown in fig. 4, in the present embodiment, the adhesive layer 40 and the reflective layer 42 are provided over the entire conversion layer 14. The adhesive layer 40 and the reflective layer 42 are not provided directly above the sensor substrate 12.

The adhesive layer 40 of the present embodiment is a light-transmitting layer, and examples of the material of the adhesive layer 40 include an acrylic adhesive, a hot-melt adhesive, and a silicone adhesive. Examples of the acrylic adhesive include urethane acrylate, acrylic resin acrylate, and epoxy acrylate. Examples of the hot-melt adhesive include thermoplastic plastics such as EVA (ethylene-vinyl acetate copolymer resin), EAA (copolymer resin of ethylene and acrylic acid), EEA (ethylene-ethyl acrylate copolymer resin), and EMMA (ethylene-methyl methacrylate copolymer).

The thicker the thickness of the adhesive layer 40 becomes, i.e., the wider the interval between the conversion layer 14 and the reflection layer 42, the more blurred the light converted by the conversion layer 14 is within the adhesive layer 40, and thus, as a result, the radiographic image obtained by the radiation detector 10 becomes a blurred image. Therefore, the thicker the thickness of the adhesive layer 40 becomes, the more the MTF (Modulation Transfer Function) and DQE (detected Quantum Efficiency) decrease, and the degree of the decrease also increases.

On the other hand, when the thickness of the adhesive layer 40 is too small, a minute air layer may be formed between the conversion layer 14 and the reflection layer 42, including a case where the adhesive layer 40 is not provided. At this time, multiple reflections of light from the conversion layer 14 toward the reflection layer 42 occur between the air layer and the conversion layer 14 and between the air layer and the reflection layer 42. If the light is attenuated by the multiple reflection, the sensitivity of the radiation detector 10 is lowered. If the thickness of the adhesion layer 40 exceeds 7 μm, the degree of decrease in DQE becomes larger, resulting in a decrease than in the case where the thickness of the adhesion layer 40 is 0 μm. That is, if the thickness of the adhesive layer 40 exceeds 7 μm, the DQE is lowered compared to the case where the adhesive layer 40 is not provided. Also, in the case where the thickness of the adhesive layer 40 is less than 2 μm, the sensitivity of the radiation detector 10 is lowered. Therefore, in the present embodiment, the thickness of the adhesive layer 40 is set to 2 μm or more and 7 μm or less. The refractive index of the adhesive layer 40 is approximately 1.5 or so, although it varies depending on the material.

The adhesive layer 40 has a function of fixing the reflective layer 42 to the conversion layer 14, and if the thickness of the adhesive layer 40 is 2 μm or more, an effect of sufficiently suppressing the deviation of the reflective layer 42 from the conversion layer 14 in the in-plane direction (the direction intersecting the thickness direction) can be obtained.

On the other hand, as shown in fig. 4, for example, the reflective layer 42 is provided on the adhesive layer 40 and covers the entire upper surface of the adhesive layer 40 itself. The reflective layer 42 has a function of reflecting the light converted by the conversion layer 14.

As the material of the reflective layer 42, an organic material is preferably used, and for example, white PET (Polyethylene Terephthalate), TiO (Polyethylene Terephthalate) and the like are preferably used₂、Al₂O₃At least 1 of foamed white PET, polyester-based highly reflective sheet, and specular reflective aluminum is used as the material. In particular, white PET is preferably used as the material from the viewpoint of reflectance.

White PET means that TiO is added to PET₂Or white pigment such as barium sulfate. The polyester-based highly reflective sheet is a sheet (film) having a multilayer structure in which a plurality of thin polyester sheets are stacked. The foamed white PET is white PET whose surface is porous.

In the present embodiment, the thickness of the reflective layer 42 is set to 10 μm or more and 40 μm or less. If the thickness of the reflection layer 42 is increased, a step between the upper surface of the outer peripheral portion of the reflection layer 42 and the upper surface of the conversion layer 14 is increased, and at least one of the adhesive layer 44 and the protective layer 46 may be lifted. Further, when the thickness of the reflection layer 42 is increased, it can be said that the reflection layer has rigidity, and therefore, the reflection layer is difficult to bend along the inclination of the peripheral edge portion of the conversion layer 14, and the processing may be difficult. Therefore, from these viewpoints, in the radiation detector 10 of the present embodiment, when white PET is used as the material of the reflective layer 42, the thickness of the reflective layer 42 is set to 40 μm or less as described above.

On the other hand, the thinner the thickness of the reflective layer 42 becomes, the lower the reflectance becomes. When the reflectance is lowered, the quality of the radiation image obtained by the radiation detector 10 also tends to be lowered. Therefore, from the viewpoint of the image quality of the radiographic image obtained by the radiation detector 10, it is preferable to set the lower limit value of the thickness of the reflective layer 42 in consideration of a desired reflectance (for example, 80%). In the radiation detector 10 of the present embodiment, when white PET is used as the material of the reflective layer 42, the thickness of the reflective layer 42 is set to 10 μm or more as described above.

On the other hand, as shown in fig. 4, for example, the adhesive layer 44 is provided from the region near the outer peripheral portion of the conversion layer 14 in the sensor substrate 12 to the region covering the end portion of the reflection layer 42. In other words, in the radiation detector 10 of the present embodiment, the adhesive layer 44 covering the entire conversion layer 14 provided with the adhesive layer 40 and the reflection layer 42 is directly fixed (adhered) to the surface of the sensor substrate 12. The adhesive layer 44 has a function of fixing the reflective layer 42 to the sensor substrate 12 and the conversion layer 14. The adhesive layer 44 also has a function of fixing the protective layer 46. Examples of the material of the adhesive layer 44 include the same material as the adhesive layer 40. In the present embodiment, the adhesive layer 44 has a stronger adhesive force than the adhesive layer 40.

Further, as shown in fig. 4, for example, the protective layer 46 is provided on the adhesive layer 44, the protective layer 46 of the present embodiment covers the entire upper surface of the adhesive layer 44, and the adhesive layer 44 covers the conversion layer 14 in a state where the upper surface is covered with the adhesive layer 40 and the reflective layer 42. The protective layer 46 has a function of protecting the conversion layer 14 from moisture such as moisture. The protective layer 46 has a function of fixing the reflective layer 42 to the sensor substrate 12 and the conversion layer 14 together with the adhesive layer 44. Examples of the material of the protective layer 46 include organic films, such as PET, PPS (PolyPhenylene Sulfide), OPP (Oriented PolyPropylene film), PEN (PolyEthylene Naphthalate), and PI. As the protective layer 46, an ALPET (registered trademark) sheet obtained by laminating aluminum by bonding an aluminum foil and an insulating sheet (film) such as polyethylene terephthalate may be used.

An antistatic layer 60 and a protective layer 62 are provided on the side of the laminated body 19 to which the radiation R is irradiated (in other words, on the 2 nd surface 11B side of the base material 11 in the sensor substrate 12). As shown in fig. 4, the antistatic layer 60 is disposed on the No. 2 surface 11B of the base material 11, and has a function of preventing the sensor substrate 12 from being charged. As the antistatic layer 60, a film using an antistatic paint "cold" (product name: cold co., LTD) is used as the antistatic layer 60 in the present embodiment.

The protective layer 62 is provided on the side of the antistatic layer 60 opposite to the side in contact with the base material 11, and has a function of preventing the sensor substrate 12 from being electrified, similarly to the antistatic layer 60. As the protective layer 62, for example, an ALPET (registered trademark) sheet obtained by laminating aluminum by bonding an aluminum foil and an insulating sheet (thin film) is used as the protective layer 62 in the present embodiment. As shown in fig. 5, the protective layer 62 is connected to a ground (ground) for discharging the electric charges accumulated in the antistatic layer 60 and the protective layer 62. In the present embodiment, as an example of the ground, a so-called frame ground in which the frame body 120 is connected to the protective layer 62 as the ground is used, but the ground to which the protective layer 62 is connected is not limited to the present embodiment, and may be a portion to which a constant potential is supplied. Further, a ground line may be applied instead of the ground. As shown in fig. 5, in the radiographic imaging device 1 of the present embodiment, a buffer material 150 is provided between the protective layer 62 and the top plate 120A of the housing 120 having the irradiation surface on which the radiation R is irradiated. The cushioning material 150 has a function of absorbing impact due to a load or the like of the subject applied to the top plate 120A of the housing 120 and absorbing an influence due to bending of the top plate 120A. The cushioning member 150 of the present embodiment has a function of absorbing irregularities generated in the frame 120A. The cushioning material 150 may be made of a material having a shore E hardness, which is a durometer hardness, similar to the absorbent layer 52 described later.

The protective layer 62 is not limited to a layer having an antistatic function, and may have at least one of a moisture-proof function and an antistatic function for the pixel region 35, and besides the ALPET (registered trademark) sheet of the present embodiment, a parylene (registered trademark) film, an insulating sheet such as PET, or the like may be used as the protective layer.

Further, the reinforcing substrate 50, the absorption layer 52, the radiation shielding layer 54, and the rigid plate 56 are provided on the side of the laminated body 19 opposite to the side irradiated with the radiation R (in other words, the side of the conversion layer 14 opposite to the side in contact with the sensor substrate 12). The reinforcing substrate 50, the absorption layer 52, the radiation shielding layer 54, and the rigid plate 56 are sequentially stacked on the conversion layer 14.

The absorption layer 52 has a function of suppressing the transmission of irregularities to the sensor substrate 12 by absorbing the irregularities generated in the conversion layers 14 of the stacked body 19 due to the irregularities of the stacked body 19 of the radiation detector 10, the casing 120, or the like.

First, unevenness generated in the laminated body 19 due to unevenness of the laminated body 19 itself, the frame body 120, or the like will be described with reference to fig. 11. Unlike the radiation detector 10 of the present embodiment, fig. 11 shows a radiation detector 10X (radiographic imaging device 1X) in a state where the reinforcing substrate 50 and the absorbing layer 52 are not provided.

The region a in fig. 11 is an example of a region including the unevenness 96A caused by the conversion layer 14. As described above, the conversion layer 14 is formed as the columnar crystals 14A on the sensor substrate 12. At this time, the radiation shielding layer 54 side of the conversion layer 14 becomes the end of the columnar crystal 14A. However, since the base material 11 of the sensor substrate 12 is relatively soft and easily bent as described above, as shown in the region a of fig. 11, the irregularities at the ends of the columnar crystals 14A may propagate to the sensor substrate 12 side, and the irregularities 96A may be generated on the sensor substrate 12 on the root side rather than on the end side of the conversion layer 14. In other words, the irregularities of the columnar crystals 14A of the conversion layer 14 may be transferred to the sensor substrate 12 on the root side.

The region B in fig. 11 is an example of a region including the irregularities 96B due to the bubbles 90 generated in the radiation shielding layer 54. The bubbles 90 generated in the radiation shielding layer 54 may cause irregularities between the radiation shielding layer 54 and the rigid plate 56. Mainly, as shown in a region B of fig. 11, the radiation shielding layer 54 may enter the conversion layer 14 side and generate unevenness in the conversion layer 14. At this time, the influence of the irregularities generated by the radiation shielding layer 54 may propagate, and irregularities 96B may be generated on the sensor substrate 12.

The region C in fig. 11 is an example of a region including the irregularities 96C caused by the irregularities 92 of the rigid plate 56. There are cases where minute irregularities are generated on the surface of the rigid plate 56, and for example, the irregularities 92 in the region C in fig. 11 are irregularities due to the recesses of the rigid plate 56, and show an example of a state where irregularities are generated on the laminated body 19 due to the irregularities 92 of the rigid plate 56. As shown in a region C of fig. 11, irregularities may be generated on the radiation shielding layer 54 due to the irregularities 92 of the rigid plate 56, and further the influence of the irregularities generated by the rigid plate 56 may be propagated, thereby generating irregularities 96C on the sensor substrate 12.

As shown in fig. 11, the base material 11 of the sensor substrate 12 may be relatively easily bent, and thus, in a case where the base material is softer than other layers (members) forming the radiation detector 10X, the influence of the irregularities caused by the radiation imaging device 1X such as the laminated body 19 and the housing 120 is propagated, and the irregularities are generated on the sensor substrate 12. In particular, when a pressure, an impact, or the like is applied to the top plate 120A of the housing 120 by applying a load of the subject or the like, the influence of the irregularities described above is likely to be transmitted to the sensor substrate 12, and thus the irregularities are likely to be generated on the sensor substrate 12. The irregularities generated in the sensor substrate 12 may appear as image unevenness on the radiation image obtained by the radiation detector 10X.

In contrast, as shown in fig. 3 to 5, the absorption layer 52 of the present embodiment is provided on the side of the laminated body 19 opposite to the side on which the radiation R is irradiated, and in the radiation detector 10 of the present embodiment, is provided on the conversion layer 14. The absorption layer 52 has a function of absorbing the influence of the irregularities caused by the laminate 19, the frame 120, or the like as described above and suppressing the influence of the irregularities from propagating to the sensor substrate 12.

The absorption layer 52 is a layer made of a soft material for absorbing the influence of the irregularities, and has a durometer hardness smaller than that of the entire laminate 19. In the method for measuring hardness in the present embodiment, a sample is mounted on an E-type durometer based on JIS K6253 and is measured after being in contact with a indenter for 15 seconds.

Specific examples of the material of the absorbent layer 52 include foams such as polyurethane foam, polyethylene, rubber sponge, and silicone foam, and polyurethane gel.

In the radiographic imaging device 1 (radiation detector 10) of the present embodiment, as shown in fig. 6, by providing the absorption layer 52, even in the region a including the irregularities of the columnar crystals 14A of the conversion layer 14, the absorption layer 52 deforms in accordance with the irregularities of the columnar crystals 14A, and the irregularities do not propagate to the sensor substrate 12.

Further, as shown in fig. 6, by providing the absorption layer 52, even in the region B where the bubbles 90 are generated by the radiation shielding layer 54, the absorption layer 52 is deformed by the bubbles 90, and the irregularities caused by the bubbles 90 do not propagate to the sensor substrate 12.

Further, as shown in fig. 6, even in the region C of the rigid plate 56 where the irregularities 92 are generated, the absorption layer 52 is deformed by the irregularities 92, and the irregularities due to the irregularities 92 do not propagate to the sensor substrate 12 by providing the absorption layer 52.

As described above, according to the radiation detector 10 of the present embodiment, the absorption layer 52 has a shape corresponding to the irregularities generated in the conversion layers 14 of the stacked body 19 due to the irregularities of the stacked body 19, the casing 120, or the like of the radiation detector 10, and therefore propagation of the irregularities to the sensor substrate 12 can be suppressed.

As shown in fig. 3 to 5, the absorption layer 52 of the present embodiment has the same size (area) as the 1 st surface 11A side of the base material 11 in the sensor substrate 12. The size of the absorption layer 52 is not limited to the embodiment shown in fig. 3 to 5, but is preferably larger than the sensor substrate 12, and preferably has an area at least larger than the conversion layer 14.

The thickness of the absorption layer 52 (thickness in the stacking direction P) is set according to the size of the unevenness caused by the stacked body 19 or the frame body 120, for example, the size of the air bubbles 90 or the unevenness 92 shown in fig. 5. The absorbent layer 52 preferably has a thickness at least greater than the size of the air bubbles 90 or the asperities 92.

The absorption layer 52 preferably has an antistatic function or conductivity for preventing the sensor substrate 12 from being charged, and the surface resistance value is preferably 10¹³Omega is less than or equal to. As the absorption layer 52 having conductivity, for example, a material in which conductive carbon is doped into polyethylene resin can be applied.

The reinforcing substrate 50 has a function of dispersing the compressive force applied to the absorbent layer 52 in the in-plane direction of the absorbent layer 52, and the absorbent layer 52 is uniformly compressed by dispersing the compressive force applied to the absorbent layer 52.

The reinforcing substrate 50 is preferably made of a material having a flexural modulus of elasticity of 150MPa or more and 2500MPa or less. The measurement method of flexural modulus of elasticity is based on JIS K7171: 2016 reference. From the viewpoint of dispersing the compressive force applied to the absorbent layer 52 in the in-plane direction of the absorbent layer 52, the reinforcing board 50 preferably has a higher flexural rigidity than the base material 11. Further, when the flexural modulus of elasticity is lowered, the flexural rigidity is also lowered, and in order to obtain a desired flexural rigidity, the thickness of the reinforcing substrate 50 needs to be increased, which increases the thickness of the entire radiation detector 10. Considering the material of the reinforcing substrate 50, it is desired to obtain more than 140000Pacm⁴The thickness of the reinforcing substrate 50 tends to be relatively thick in the case of the bending rigidity of (2). Therefore, if appropriate rigidity is obtained and the thickness of the entire radiation detector 10 is taken into consideration, the flexural modulus of the material for the reinforcing substrate 50 is more preferably 150MPa or more and 2500MPa or less. The bending rigidity of the reinforcing substrate 50 is preferably 540Pacm⁴Above 140000Pacm⁴The following.

The reinforcing substrate 50 of the present embodiment is a substrate made of plastic. The plastic material of the reinforcing substrate 50 is preferably a thermoplastic resin, and may be at least one of PC (Polycarbonate), PET, Styrene, acrylic, polyacetate, nylon, polypropylene, ABS (Acrylonitrile Butadiene Styrene), engineering plastic, PET, and polyphenylene oxide. Among these, the reinforcing substrate 50 is preferably at least one of polypropylene, ABS, engineering plastic, PET, and polyphenylene ether, more preferably at least one of styrene, acrylic, polyacetate, and nylon, and even more preferably at least one of PC and PET.

The radiation shielding layer 54 provided above the reinforcing substrate 50 has a function of shielding the radiation R that has passed through the laminated body 19 and suppressing transmission of the radiation R to the outside of the housing 120. As the radiation shielding layer 54, for example, a plate such as lead may be used.

Further, a rigid plate 56 provided above the radiation shielding layer 54 supports the radiation detector 10. The rigid plate 56 is more rigid than the sensor substrate 12, and carbon or the like may be used, for example.

The housing 120 shown in fig. 5, which houses the radiation detector 10 of the present embodiment, is light, and preferably made of a material having a sufficiently high elastic modulus, and having a low radiation R absorption rate, particularly X-rays, and high rigidity. The material of the frame 120 is preferably a material having a flexural modulus of elasticity of 10000MPa or more. Carbon or CFRP (Carbon Fiber Reinforced Plastics) having a flexural modulus of elasticity of about 20000 to 60000MPa can be preferably used as a material of the frame body 120.

In capturing a radiographic image by the radiographic imaging device 1, a load from the subject is applied to the top plate 120A of the housing 120. If the rigidity of the housing 120 is insufficient, the sensor substrate 12 may be bent by a load from the subject, and a defect such as damage to the pixel 30 may occur. The radiation detector 10 is housed in the housing 120 made of a material having a flexural modulus of elasticity of 10000MPa or more, and thus the sensor substrate 12 can be prevented from being deflected by a load from the subject.

As shown in fig. 5, the radiation detector 10, the power supply section 108, and the control board 110 are arranged in a direction intersecting the incident direction of the radiation R in the housing 120.

The control substrate 110 is a substrate on which an image memory 380 for storing image data corresponding to electric charges read from the pixels 30 of the sensor substrate 12, a control unit 382 for controlling reading of electric charges from the pixels 30, and the like are formed, and is electrically connected to the pixels 30 of the sensor substrate 12 via a flexible cable 112 including a plurality of signal wirings. In the radiographic imaging device 1 shown in fig. 5, the flexible cable 112 is provided with a so-called COF (Chip on Film) in which the driving unit 103 that controls the switching state of the TFTs 32 of the pixels 30 under the control of the control unit 382 and the signal processing unit 104 that generates and outputs image data corresponding to the electric charges read from the pixels 30, but at least one of the driving unit 103 and the signal processing unit 104 may be formed on the control substrate 110.

The control board 110 is connected to the image memory 380 formed on the control board 110, the power supply unit 108 for supplying power to the control unit 382, and the like, via the power supply line 114.

In addition, as in the example shown in fig. 5, the thickness of each of the power supply section 108 and the control substrate 110 is often thicker than that of the radiation detector 10. In this case, as in the example shown in fig. 7, the thickness of the portion of the housing 120 where the radiation detector 10 is provided may be thinner than the thickness of the portion of the housing 120 where the power supply section 108 and the control substrate 110 are provided, respectively. In addition, in the case where the thickness of the portion of the housing 120 in which the power supply unit 108 and the control board 110 are provided is different from the thickness of the portion of the housing 120 in which the radiation detector 10 is provided, if a step is generated in the boundary portion between the two portions, there is a possibility that the subject in contact with the boundary portion 120B feels uncomfortable, and the like, and therefore, the form of the boundary portion 120B is preferably in a tilted state.

Thus, an extremely thin portable electronic cassette corresponding to the thickness of the radiation detector 10 can be configured.

In this case, for example, the material of the housing 120 may be different between the portion of the housing 120 where the power supply unit 108 and the control board 110 are provided and the portion of the housing 120 where the radiation detector 10 is provided. Further, for example, a portion of the housing 120 where the power supply section 108 and the control board 110 are provided may be disposed separately from a portion of the housing 120 where the radiation detector 10 is provided.

As shown in fig. 8, the radiographic imaging device 1 may be housed in the housing 120 in a state in which the radiation detector 10, the control board 110, and the power supply unit 108 are arranged in this order from the top 120A side to which the radiation R is irradiated.

As described above, the radiation detector 10 of the present embodiment includes: a sensor substrate 12 in which a plurality of pixels 30 that accumulate charges generated according to light converted from radiation R are formed on a pixel region 35 of the flexible base material 11; a conversion layer 14 that is provided on the 1 st surface 11A of the substrate 11 on which the pixel region 35 is provided, and that converts the radiation R into light; an absorption layer 52 that is provided on the side of the laminated body 19 in which the sensor substrate 12 and the conversion layer 14 are laminated, the side being opposite to the side irradiated with the radiation R, and that absorbs the influence of the irregularities generated in the conversion layer 14 on the sensor substrate 12; and a rigid plate 56 provided on the side of the absorption layer 52 opposite to the side facing the laminated body 19 and having higher rigidity than the sensor substrate 12.

As described above, according to the radiation detector 10 of the present embodiment, the absorption layer 52 has a shape corresponding to the irregularities generated in the conversion layers 14 of the stacked body 19 due to the irregularities of the stacked body 19, the casing 120, or the like of the radiation detector 10, and therefore, the influence of the irregularities on the sensor substrate 12 can be suppressed. Therefore, by suppressing the occurrence of irregularities on the sensor substrate 12, the radiation detector 10 according to the present embodiment can suppress image unevenness of a radiographic image and the like due to the irregularities of the sensor substrate 12, and can improve the image quality of the radiographic image.

The position of providing the reinforcing substrate 50 is not limited to the position shown in the present embodiment (see fig. 4), and may be provided on the side opposite to the laminated body 19, specifically, on the side of the antistatic layer 60 and the protective layer 62, as shown in fig. 9. In this case, the reinforcing substrate 50 may be provided between the antistatic layer 60 and the sensor substrate 12, for example, without being limited to the example shown in fig. 9.

Although the radiation detector 10 (radiographic imaging device 1) of the ISS system has been described above, the radiation detector 10 (radiographic imaging device 1) of the pss (networking Side sampling) system, which irradiates the radiation R from the conversion layer 14 Side, may be the radiation detector 10 (radiographic imaging device 1) of the ISS system, as shown in fig. 10. In the radiation detector 10 shown in fig. 10, the absorption layer 52 that influences the sensor substrate 12 by the irregularities generated in the absorption conversion layer 14 is also provided on the side of the laminated body 19 in which the sensor substrate 12 and the conversion layer 14 are laminated, the side being opposite to the side irradiated with the radiation R. The sensor device further includes a rigid plate 56 that is provided on the side of the absorption layer 52 opposite to the side facing the laminated body 19 and that has higher rigidity than the sensor substrate 12.

Therefore, in the radiation detector 10 shown in fig. 10, the absorption layer 52 has a shape corresponding to the irregularities generated in the conversion layers 14 of the stacked body 19 due to the irregularities of the stacked body 19, the casing 120, or the like of the radiation detector 10, and therefore, the influence of the irregularities on the sensor substrate 12 can be suppressed. Therefore, by suppressing the occurrence of irregularities on the sensor substrate 12, the radiation detector 10 according to the present embodiment can suppress image unevenness of a radiographic image and the like due to the irregularities of the sensor substrate 12, and can improve the image quality of the radiographic image.

In the above embodiment, the pixels 30 are two-dimensionally arranged in a matrix as shown in fig. 1, but the present invention is not limited to this, and may be one-dimensionally arranged or honeycomb-arranged, for example. The shape of the pixel is not limited, and may be a rectangle or a polygon such as a hexagon. Further, the shape of the pixel region 35 is not limited, as a matter of course.

The shape and the like of the conversion layer 14 are not limited to those of the above embodiments. In the above embodiment, the description has been given of the form in which the conversion layer 14 has a rectangular shape in the same manner as the pixel region 35, but the form of the conversion layer 14 may not have the same shape as the pixel region 35. The shape of the pixel region 35 may be, for example, another polygonal shape, or may be a circular shape instead of a rectangular shape.

In the above-described embodiment, the description has been given of the case where the conversion layer 14 of the radiation detector 10 is a scintillator including CsI as an example, but the conversion layer 14 may be GOS (Gd)₂O₂S: tb) and the like into an adhesive such as a resin. The conversion layer 14 using GOS is formed, for example, as follows: the adhesive in which GOS is dispersed is directly applied to the sensor substrate 12, the release layer, or the like, and then dried and cured. As a method for forming the conversion layer 14, for example, a Giza method may be employed in which a coating liquid is applied to a region where the conversion layer 14 is formed while controlling the thickness of the coating film. In this case, before the application of the GOS-dispersed adhesive, a surface treatment for activating the surface of the pixel region 35 may be performed. Further, a surface protective film may be provided as an interlayer insulating film on the surface of the pixel region 35.

In addition, the configurations of the radiographic imaging device 1, the radiation detector 10, and the like described in the above embodiments are examples, and it goes without saying that modifications may be made depending on the situation without departing from the scope of the present invention.

All disclosures of japanese patent application No. 2019-086596, filed on 26.4.2019, are incorporated herein by reference.

All documents, patent applications, and technical standards described in the present specification are incorporated by reference into the present specification to the same extent as if each individual document, patent application, and technical standard incorporated by reference was specifically and individually described.

Description of the symbols

1, 1X-ray image photographing device, 10, 10X-ray detector, 11-substrate, 11A-1 st surface, 11B-2 nd surface, 11P-fine particles, 11L-fine particle layer, 12-sensor substrate, 14-conversion layer, 14A-columnar crystals, 19-laminate, 30-pixel, 32-switching element (TFT), 34-sensor section, 35-pixel region, 36-signal wiring, 38-scanning wiring, 39-common wiring, 40-adhesive layer, 42-reflective layer, 44-adhesive layer, 46-protective layer, 50-reinforcing substrate, 52-absorbing layer, 54-radiation shielding layer, 56-rigid plate, 60-antistatic layer, 62-protective layer, 90-bubbles, 92, 96A, 96B, 96C-bumps, 103-driving section, 104-signal processing section, 108-power section, 110-control substrate, 112-flexible cable, 114-power line, 117-protective layer, 120-frame, 120A-top plate, 120B-boundary section, 150-buffer material, 380-image memory, 382-control section, a, B, C-region, P-stacking direction, R-radiation.