Patent Description:
In the related art, radiographic imaging apparatuses that perform radiographic imaging for medical diagnosis have been known. A radiation detector for detecting radiation transmitted through a subject and generating a radiographic image is used for such radiographic imaging apparatuses.

As this radiation detector, there is one comprising a conversion layer, such as a scintillator, which converts radiation into light, and a sensor substrate in which a plurality of pixels, which accumulate electric charges generated in response to light converted in the conversion layer, are provided in a pixel region of a base material. As a base material of a sensor substrate of such a radiation detector, one using a flexible base material is known (for example, refer to <CIT>). By using the flexible base material, for example, the weight of the radiographic imaging apparatuses (radiation detector) can be reduced, and a subject may be easily imaged. Radiographic imaging apparatus is disclosed in <CIT> and <CIT>. Another example of a radiographic imaging apparatus is shown in <CIT>.

There is a case where fine irregularities are generated in a laminate or the like in which the conversion layer is laminated on the sensor substrate. In a case where a load or impact is applied to the radiographic imaging apparatus in the capturing of the radiographic image, there is a case where the irregularities generated in the laminate propagate to the flexible base material, and the quality of the radiographic image generated by the radiation detector deteriorates.

The present disclosure provides a radiation detector and a radiographic imaging apparatus capable of improving the quality of a radiographic image.

A radiation detector according to a first aspect of the present disclosure is as defined by claim <NUM>.

In an embodiment a durometer hardness of the absorption layer is smaller than a durometer hardness of the entire laminate.

In an embodiment, the absorption layer has a surface resistance value of <NUM><NUM> Ω or less.

In an embodiment, the reinforcing substrate has a bending elastic modulus of <NUM> MPa or more and <NUM>,<NUM> MPa or less.

In an embodiment, the reinforcing substrate has a bending stiffness of <NUM> Pacm<NUM> or more and <NUM>,<NUM> Pacm<NUM> or less.

An embodiment may further comprise a radiation-shielding layer shielding the radiation and provided between the absorption layer and the rigid plate.

In an embodiment, the rigid plate is a plate having carbon as a material.

An embodiment may further comprise a buffer member that is provided on a side of the laminate on which the radiation is incident.

In an embodiment, the conversion layer contains columnar crystals of CsI.

An embodiment may further comprise a control unit that outputs a control signal for reading out electric charges accumulated in the plurality of pixels; a drive unit that reads out the electric charges from the plurality of pixels in accordance with the control signal; and a signal processing unit that receives electrical signals according to the electric charges read from the plurality of pixels and generates image data according to the received electrical signals to output the image data to the control unit.

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

In addition, the present embodiments do not limit the present invention.

The radiation detector of the present embodiment has a function of detecting radiation transmitted through a subject to output image information representing a radiographic image of the subject. The radiation detector of the present embodiment comprises a sensor substrate and a conversion layer that converts radiation into light (refer to a sensor substrate <NUM> and a conversion layer <NUM> of the radiation detector <NUM> in <FIG>).

First, an example of the configuration of the sensor substrate <NUM> in the radiation detector of the present embodiment will be described with reference to <FIG>. In addition, the sensor substrate <NUM> of the present embodiment is a substrate in which a plurality of pixels <NUM> are formed in a pixel region <NUM> of the base material <NUM>.

The base material <NUM> is made of resin and has flexibility. The base material <NUM> is, for example, a resin sheet containing plastic such as polyimide. The thickness of the base material <NUM> may be a thickness in which desired flexibility is obtained in accordance with the hardness of the material, the size of the sensor substrate <NUM>, and the like. For example, in a case where the base material <NUM> is a resin sheet, the thickness thereof may be <NUM> to <NUM> and more preferably <NUM> to <NUM>.

In addition, the base material <NUM> has characteristics capable of withstanding the manufacture of the pixels <NUM> to be described in detail below and has characteristics capable of withstanding the manufacture of amorphous silicon thin film transistor (a-Si TFT) in the present embodiment. As such a property of the base material <NUM>, the coefficient of thermal expansion at <NUM> to <NUM> is preferably about the same as that of an amorphous silicon (Si) wafer (for example, ± <NUM> ppm/K), and specifically, preferably <NUM> ppm/K or less. Additionally, as the percentage of thermal shrinkage of the base material <NUM>, the percentage of thermal shrinkage in a machine direction (MD) at <NUM> in a state where the thickness is <NUM> is preferably <NUM>% or less. Additionally, it is preferable that the elastic modulus of the base material <NUM> does not have a transition point that general polyimide has, in a temperature range of <NUM> to <NUM>, and the elastic modulus at <NUM> is <NUM> GPa or more.

Additionally, as shown in <FIG>, it is preferable that the base material <NUM> of the present embodiment has, on a surface opposite to a side where the conversion layer <NUM> is provided, a fine particle layer <NUM> containing inorganic fine particles 11P having an average particle diameter of <NUM> or more and <NUM> or less, which absorbs backscattered rays caused by itself in order to suppress the backscattered rays. In addition, as the inorganic fine particles 11P, in the case of the resinous base material <NUM>, it is preferable to use an inorganic material of which the atomic number is larger than the atoms constituting the organic material that is the base material <NUM> and of which the atomic number is <NUM> or less. Specific examples of such fine particles 11P include SiO<NUM> that is an oxide of Si having an atomic number of <NUM>, MgO that is an oxide of Mg having an atomic number of <NUM>, Al<NUM>O<NUM> that is an oxide of Al having an atomic number of <NUM>, TiO<NUM> that is an oxide of Ti having an atomic number of <NUM>, and the like. A specific example of the resin sheet having such characteristics is XENOMAX (registered trademark).

In addition, the above thicknesses in the present embodiment were measured using a micrometer. The coefficient of thermal expansion was measured according to JIS K7197:<NUM>. In addition, the measurement was performed by cutting out test pieces from a main surface of the base material <NUM> while changing the angle by <NUM> degrees, measuring the coefficient of thermal expansion of each of the cut-out test pieces, and setting the highest value as the coefficient of thermal expansion of the base material <NUM>. The coefficient of thermal expansion is measured at intervals of <NUM> between -<NUM> and <NUM> in a machine direction (MD) and a transverse direction (TD), and (ppm/°C) is converted to (ppm/K). For the measurement of the coefficient of thermal expansion, the TMA4000S apparatus made by MAC Science Co. is used, sample length is <NUM>, sample width is <NUM>, initial load is <NUM>/mm<NUM>, temperature rising rate is <NUM>/min, and the atmosphere is in argon. The elastic modulus was measured according to JIS K7171:<NUM>. In addition, the measurement was performed by cutting out test pieces from the main surface of the base material <NUM> while changing the angle by <NUM> degrees, performing a tensile test for each of the cut-out test pieces, and setting the highest value as the elastic modulus of the base material <NUM>.

Each of the pixels <NUM> includes a sensor unit <NUM> that generates and accumulates electric charges in response to the light converted by the conversion layer, and a switching element <NUM> that reads out the electric charges accumulated by the sensor unit <NUM>. In the present embodiment, as an example, a thin film transistor (TFT) is used as the switching element <NUM>. For that reason, in the following description, the switching element <NUM> is referred to as a "TFT <NUM>".

The plurality of pixels <NUM> are two-dimensionally arranged in one direction (a scanning wiring direction corresponding to a transverse direction of <FIG>, hereinafter referred to as a "row direction"), and a direction intersecting the row direction (a signal wiring direction corresponding to the longitudinal direction of <FIG>, hereinafter referred as a "column direction") in a pixel region <NUM> of the sensor substrate <NUM>. Although an array of the pixels <NUM> is shown in a simplified manner in <FIG>, for example, <NUM> × <NUM> pixels <NUM> are arranged in the row direction and the column direction.

Additionally, a plurality of scanning wiring lines <NUM> for controlling switching states (ON and OFF) of the TFTs <NUM>, and a plurality of signal wiring lines <NUM>, which are provided for respective columns of the pixels <NUM> and from which electric charges accumulated in the sensor units <NUM> are read out, are provided in a mutually intersecting manner in the radiation detector <NUM>. The plurality of scanning wiring lines <NUM> are respectively connected to a drive unit <NUM> (refer to <FIG>) outside the radiation detector <NUM> via pads (not shown), respectively, provided in the sensor substrate <NUM>, and thereby, control signals, which are output from the drive unit <NUM> to control the switching states of the TFTs <NUM>, flow to the plurality of scanning wiring lines <NUM>, respectively. Additionally, the plurality of signal wiring lines <NUM> are respectively connected to a signal processing unit <NUM> (refer to <FIG>) outside the radiation detector <NUM> via pads (not shown), respectively, provided in the sensor substrate <NUM>, and thereby, electric charges read from the respective pixels <NUM> are output to the signal processing unit <NUM>.

Additionally, common wiring lines <NUM> are provided in a wiring direction of the signal wiring lines <NUM> at the sensor units <NUM> of the respective pixels <NUM> in order to apply bias voltages to the respective pixels <NUM>. Bias voltages are applied to the respective pixels <NUM> from a bias power source by connecting the common wiring lines <NUM> to the bias power source outside the radiation detector <NUM> via pads (not shown) provided in the sensor substrate <NUM>.

The radiographic imaging apparatus <NUM> including the radiation detector <NUM> of the present embodiment will be described in more detail with reference to <FIG>. The radiation detector <NUM> of the present embodiment is an irradiation side sampling (ISS) type radiation detector in which a laminate <NUM> on which the conversion layer <NUM> is formed is provided on the sensor substrate <NUM> and radiation R is radiated from the sensor substrate <NUM> side. <FIG> is a plan view of an example of the radiographic imaging apparatus <NUM> including the radiation detector <NUM> of the present embodiment as viewed from a side where the sensor substrate <NUM> is formed. In other words, <FIG> is a plan view of the radiographic imaging apparatus <NUM> (radiation detector <NUM>) as viewed from a side to which the radiation R is radiated. Additionally, <FIG> is a cross-sectional view taken along line A-A of an example of the radiation detector <NUM> in <FIG>. Moreover, <FIG> is a cross-sectional view of an example of the radiographic imaging apparatus <NUM> in a state where the radiation detectors <NUM> of <FIG> and <FIG> are housed in a housing <NUM>.

In the following, here, the term "on" in the structure of the radiation detector <NUM> means "on" in a positional relationship with reference to the sensor substrate <NUM> side in <FIG>. For example, the conversion layer <NUM> is provided on the sensor substrate <NUM>.

As shown in <FIG>, the radiographic imaging apparatus <NUM> of the present embodiment includes a protective layer <NUM>, an antistatic layer <NUM>, a sensor substrate <NUM>, the conversion layer <NUM>, a reinforcing substrate <NUM>, an absorption layer <NUM>, and a radiation-shielding layer <NUM>, and a rigid plate <NUM>. Additionally, as shown in <FIG>, in the radiographic imaging apparatus <NUM>, the protective layer <NUM>, the antistatic layer <NUM>, the sensor substrate <NUM>, the conversion layer <NUM>, the reinforcing substrate <NUM>, the absorption layer <NUM>, the radiation-shielding layer <NUM>, and the rigid plate <NUM> are housed in the housing <NUM> in this order from the side to which the radiation R is radiated.

As shown in <FIG>, the conversion layer <NUM> of the present embodiment is provided on a partial region of the sensor substrate <NUM> including the pixel region <NUM> on the first surface 11A of the base material <NUM>. In this way, the conversion layer <NUM> of the present embodiment is not provided on the region of an outer peripheral portion on the first surface 11A of the base material <NUM>.

In the present embodiment, a scintillator including CsI (cesium iodide) is used as an example of the conversion layer <NUM>. It is preferable that such a scintillator includes, for example, CsI:Tl (cesium iodide to which thallium is added) or CsI:Na (cesium iodide to which sodium is added) having an emission spectrum of <NUM> to <NUM> at the time of X-ray radiation. In addition, the emission peak wavelength in a visible light region of CsI:Tl is <NUM>.

In the radiation detector <NUM> of the present embodiment, as in the example shown in <FIG>, the conversion layer <NUM> is directly formed on the sensor substrate <NUM> as strip-shaped columnar crystals (not shown) by vapor-phase deposition methods, such as a vacuum vapor deposition method, a sputtering method, and a chemical vapor deposition (CVD) method. For example, in a case where CsI:Tl is used as the conversion layer <NUM>, a vacuum vapor deposition method is used as a method of forming the conversion layer <NUM>. In the vacuum vapor deposition method, CsI:Tl is heated and gasified by heating means, such as a resistance heating-type crucible in an environment with a vacuum degree of <NUM> Pa to <NUM> Pa, and CsI:Tl is deposited on the sensor substrate <NUM> with the temperature of the sensor substrate <NUM> as the room temperature (<NUM>) to <NUM>. As the thickness of the conversion layer <NUM>, <NUM> to <NUM> is preferable.

In addition, in the present embodiment, end parts of columnar crystals of the conversion layer <NUM> on a base point side (the sensor substrate <NUM> side in the present embodiment) in a growth direction are referred to as "roots", and sharpened end parts opposite to the roots in the growth direction are referred to as "tips". In addition, it is preferable that a buffer layer (not shown) is provided between the sensor substrate <NUM> and the conversion layer <NUM>. As the buffer layer in this case, a polyimide (PI) film or a parylene (registered trademark) film is used.

Additionally, as shown in <FIG> and <FIG>, the radiation detector <NUM> of the present embodiment comprises a pressure-sensitive adhesive layer <NUM>, a reflective layer <NUM>, an adhesive layer <NUM>, and a protective layer <NUM>. In addition, in the following, a direction in which the sensor substrate <NUM> and the conversion layer <NUM> are lined up (upward-downward direction in <FIG>) is referred to as a lamination direction (refer to <FIG>, a lamination direction P).

In the present embodiment, as an example, as shown in <FIG>, the pressure-sensitive adhesive layer <NUM> and the reflective layer <NUM> are provided on the entire conversion layer <NUM>. Additionally, the pressure-sensitive adhesive layer <NUM> and the reflective layer <NUM> are not directly provided on the sensor substrate <NUM>.

The pressure-sensitive adhesive layer <NUM> of the present embodiment is a light-transmitting layer, and examples of the material of the pressure-sensitive adhesive layer <NUM> include an acrylic pressure sensitive adhesive, a hot-melt pressure sensitive adhesive, and a silicone adhesive. Examples of the acrylic pressure sensitive adhesive include urethane acrylate, acrylic resin acrylate, epoxy acrylate, and the like. Examples of the hot-melt pressure sensitive adhesive include thermoplastics, such as ethylene-vinyl acetate copolymer resin (EVA), ethylene-acrylate copolymer resin (EAA), ethylene-ethyl acrylate copolymer resin (EEA), and ethylene-methyl methacrylate copolymer (EMMA).

As the thickness X of the pressure-sensitive adhesive layer <NUM> increases (that is, as the interval between the conversion layer <NUM> and the reflective layer <NUM> increases), the light converted by the conversion layer <NUM> is blurred within the pressure-sensitive adhesive layer <NUM>. Therefore, the radiographic image obtained by the radiation detector <NUM> becomes a blurred image as a result. For that reason, as the thickness of the pressure-sensitive adhesive layer <NUM> increases, modulation transfer function (MTF) and detective quantum efficiency (DQE) decreases, and the degree of decrease also increases.

On the other hand, in a case where the thickness of the pressure-sensitive adhesive layer <NUM> is made too small, including a case where the pressure-sensitive adhesive layer <NUM> is not provided, there is a case where a minute air layer is formed between the conversion layer <NUM> and the reflective layer <NUM>. In this case, the multiple reflection of the light directed from the conversion layer <NUM> to the reflective layer <NUM> occurs between the air layer and the conversion layer <NUM> and between the air layer and the reflective layer <NUM>. In a case where the light is attenuated by the multiple reflection, the sensitivity of the radiation detector <NUM> decreases. In a case where the thickness of the pressure-sensitive adhesive layer <NUM> exceeds <NUM>, the degree of decrease in DQE becomes larger and is lower than in a case where the thickness of the pressure-sensitive adhesive layer <NUM> is <NUM>). That is, in a case where the thickness of the pressure-sensitive adhesive layer <NUM> exceeds <NUM>, the DQE is lower than in a case where the pressure-sensitive adhesive layer <NUM> is not provided. Additionally, in a case where the thickness of the pressure-sensitive adhesive layer <NUM> is less than <NUM>, the sensitivity of the radiation detector <NUM> decreases. Thus, in the present embodiment, the thickness of the pressure-sensitive adhesive layer <NUM> is set to <NUM> or more and <NUM> or less. In addition, the refractive index of the pressure-sensitive adhesive layer <NUM> is approximately <NUM>, although the refractive index depends on the material.

In addition, the pressure-sensitive adhesive layer <NUM> has a function of fixing the reflective layer <NUM> to the conversion layer <NUM>. However, in a case where the thickness of the pressure-sensitive adhesive layer <NUM> is <NUM> or more, it is possible to obtain a sufficient effect of suppressing the deviation of the reflective layer <NUM> in an in-plane direction (a direction intersecting the thickness direction) with respect to the conversion layer <NUM>.

Meanwhile, as an example, as shown in <FIG>, the reflective layer <NUM> is provided on the pressure-sensitive adhesive layer <NUM> and covers the entire upper surface of the pressure-sensitive adhesive layer <NUM> itself. The reflective layer <NUM> has a function of reflecting the light converted by the conversion layer <NUM>.

As a material of the reflective layer <NUM>, it is preferable to use an organic material, and it is preferable to use, for example, at least one of white polyethylene terephthalate (PET), TiO<NUM>, Al<NUM>O<NUM>, foamed white PET, a polyester-based high-reflection sheet, specular reflection aluminum, or the like. Particularly, it is preferable to use the white PET as the material from a viewpoint of reflectivity.

In addition, the white PET is obtained by adding a white pigment, such as TiO<NUM> or barium sulfate, to PET. Additionally, the polyester-based high-reflection sheet is a sheet (film) having a multilayer structure in which a plurality of thin polyester sheets are laminated. Additionally, the foamed white PET is a white PET of which the surface is porous.

In the present embodiment, the thickness of the reflective layer <NUM> is <NUM> or more and <NUM> or less. In a case where the thickness of the reflective layer <NUM> is increased, there is a case where a level difference between an upper surface of an outer peripheral portion of the reflective layer <NUM> and an upper surface of the conversion layer <NUM> increases and at least one of the adhesive layer <NUM> or the protective layer <NUM> is lifted. Additionally, in a case where the thickness of the reflective layer <NUM> increases, a so-called stiffness state is brought about. Therefore, there is a case where bending does not occur easily along the inclination of the peripheral edge part of the conversion layer <NUM> and is not easily processed. For that reason, from these viewpoints, in the radiation detector <NUM> of the present embodiment, in a case where the white PET is used as the material of the reflective layer <NUM>, the thickness of the reflective layer <NUM> is set to <NUM> or less as described above.

On the other hand, as the thickness of the reflective layer <NUM> decreases, reflectivity decreases. In a case where the reflectivity decreases, the quality of a radiographic image to be obtained by the radiation detector <NUM> also tends to deteriorate. For that reason, from the viewpoint of the quality of the radiographic image obtained by the radiation detector <NUM>, it is preferable to set the lower limit of the thickness of the reflective layer <NUM> in consideration of a desired reflectivity (for example, <NUM>%). In the radiation detector <NUM> of the present embodiment, in a case where the white PET is used as the material of the reflective layer <NUM>, the thickness of the reflective layer <NUM> is set to <NUM> or more as described above.

Meanwhile, as an example, as shown in <FIG>, the adhesive layer <NUM> is provided from above a region in the vicinity of an outer peripheral portion of the conversion layer <NUM> in the sensor substrate <NUM> to a region covering an end part of the reflective layer <NUM>. In other words, in the radiation detector <NUM> of the present embodiment, the adhesive layer <NUM> that covers the entire conversion layer <NUM> in which the pressure-sensitive adhesive layer <NUM> and the reflective layer <NUM> are provided is directly fixed (adhered) to the surface of the sensor substrate <NUM>. The adhesive layer <NUM> has a function of fixing the reflective layer <NUM> to the sensor substrate <NUM> and the conversion layer <NUM>. Additionally, the adhesive layer <NUM> has a function of fixing the protective layer <NUM>. Examples of the material of the adhesive layer <NUM> include the same materials as the pressure-sensitive adhesive layer <NUM>. In addition, in the present embodiment, the adhesive force of the adhesive layer <NUM> is stronger than the adhesive force of the pressure-sensitive adhesive layer <NUM>.

Moreover, as an example, as shown in <FIG>, the protective layer <NUM> is provided on the adhesive layer <NUM>, and the protective layer <NUM> of the present embodiment covers the entire upper surface of the adhesive layer <NUM> that covers the conversion layer <NUM> in a state in which the upper surface thereof is covered with the pressure-sensitive adhesive layer <NUM> and the reflective layer <NUM>. The protective layer <NUM> has a function of protecting the conversion layer <NUM> from moisture, such as humidity. Additionally, the protective layer <NUM> has a function of fixing the reflective layer <NUM> to the sensor substrate <NUM> and the conversion layer <NUM> together with the adhesive layer <NUM>. Examples of the material of the protective layer <NUM> include organic films, and specifically include PET, polyphenylene sulfide (PPS), biaxially oriented polypropylene film (OPP), polyethylene naphthalate (PEN), PI, and the like. Additionally, as the protective layer <NUM>, an ALPET (registered trademark) sheet obtained by laminating aluminum, for example by causing aluminum foil to adhere to an insulating sheet (film), such as polyethylene terephthalate may be used.

Additionally, the antistatic layer <NUM> and the protective layer <NUM> are provided on the side of the laminate <NUM> to which the radiation R is radiated, in other words, on a second surface 11B side of the base material <NUM> in the sensor substrate <NUM>. As shown in <FIG>, the antistatic layer <NUM> is provided on the second surface 11B of the base material <NUM> and has a function of preventing the sensor substrate <NUM> from being charged. As an example, in the antistatic layer <NUM> of the present embodiment, a film using an antistatic paint "Colcoat" (product name: manufactured by Colcoat Co. ) is used as the antistatic layer <NUM>.

The protective layer <NUM> is provided on the side of the antistatic layer <NUM> opposite to a side in contact with the base material <NUM>, and has a function of preventing the sensor substrate <NUM> from being charged, similar to the antistatic layer <NUM>. As an example, in the protective layer <NUM> of the present embodiment, an Alpet (registered trademark) sheet in which aluminum is laminated by causing an aluminum foil to adhere to an insulating sheet (film) is used as the protective layer <NUM>. Additionally, as shown in <FIG>, the protective layer <NUM> is connected to a ground for discharging the electric charges that stay in the antistatic layer <NUM> and the protective layer <NUM>. In the present embodiment, as an example of the ground, a so-called frame ground in which the housing <NUM> is connected to the protective layer <NUM> as a ground is used, but the ground connecting the protective layer <NUM> is not limited to the present embodiment and may be a part that supplies a constant potential. Additionally, earth may be applied instead of the ground. Additionally, as shown in <FIG>, in the radiographic imaging apparatus <NUM> of the present embodiment, the buffer member <NUM> is provided between the protective layer <NUM> and the top plate 120A having an irradiation surface to which the radiation R is radiated in the housing <NUM>. The buffer member <NUM> has a function of absorbing an impact due to a load of a subject applied to the top plate 120A of the housing <NUM> and absorbing the influence of deflection of the top plate 120A. Additionally, the buffer member <NUM> of the present embodiment has a function of absorbing irregularities generated in the housing 120A. Examples of the buffer member <NUM> include a material having a Shore E hardness, which is a durometer hardness, similar to the absorption layer <NUM> described below.

In addition, the protective layer <NUM> is not limited to a layer having an antistatic function, and may have at least one of a moistureproof function or an antistatic function for the pixel region <NUM>. In addition to the Alpet (registered trademark) sheet of the present embodiment, a parylene (registered trademark) film, an insulating sheet such as PET, or the like can be used as the protective layer.

Moreover, the reinforcing substrate <NUM>, the absorption layer <NUM>, the radiation-shielding layer <NUM>, and the rigid plate <NUM> are provided on the side of the laminate <NUM> opposite to the side to which the radiation R is radiated, in other words, on the side of the conversion layer <NUM> opposite to the side in contact with the sensor substrate <NUM>. The reinforcing substrate <NUM>, the absorption layer <NUM>, the radiation-shielding layer <NUM>, and the rigid plate <NUM> are laminated on the conversion layer <NUM> in this order.

The absorption layer <NUM> has a function of absorbing the irregularities generated in the conversion layer <NUM> of the laminate <NUM> due to the irregularities of the laminate <NUM> of the radiation detector <NUM>, the housing <NUM>, or the like, thereby suppressing the propagation of the irregularities to the sensor substrate <NUM>.

First, the irregularities generated in the laminate <NUM> due to the irregularities of the laminate <NUM> itself, the housing <NUM>, or the like will be described with reference to <FIG> shows a radiation detector 10X (radiographic imaging apparatus 1X) in a state where the reinforcing substrate <NUM> and the absorption layer <NUM> are not provided, unlike the radiation detector <NUM> of the present embodiment.

A region A of <FIG> is an example of a region including irregularities 96A caused by the conversion layer <NUM>. As described above, the conversion layer <NUM> is formed as columnar crystals 14A on the sensor substrate <NUM>. In this case, the radiation-shielding layer <NUM> side of the conversion layer <NUM> is tips of the columnar crystals 14A. However, since the base material <NUM> of the sensor substrate <NUM> is relatively soft and easily deflected as described above, as shown in the region A of <FIG>, there is a case where the irregularities of the tips of the columnar crystals 14A are propagated to the sensor substrate <NUM> side, and the irregularities 96A are generated not on the distal end side of the conversion layer <NUM> but on the sensor substrate <NUM> on the root side. So to speak, there is a case where the irregularities of the columnar crystals 14A of the conversion layer <NUM> are transferred to the sensor substrate <NUM> on the root side.

Additionally, the region B of <FIG> is an example of a region including irregularities 96B caused by bubbles <NUM> generated in the radiation-shielding layer <NUM>. There is a case where irregularities are generated between the radiation-shielding layer <NUM> and the rigid plate <NUM> due to the bubbles <NUM> generated in the radiation-shielding layer <NUM>. Mainly, as shown in the region B of <FIG>, there is a case where the radiation-shielding layer <NUM> enters the conversion layer <NUM> side and the irregularities are generated in the conversion layer <NUM>. In this case, there is a case where the influence of the irregularities generated by the radiation-shielding layer <NUM> is propagated, so that the irregularities 96B are generated in the sensor substrate <NUM>.

Additionally, a region C of <FIG> is an example of a region including irregularities 96C caused by the irregularities <NUM> of the rigid plate <NUM>. There is a case where fine irregularities are generated in the surface of the rigid plate <NUM>. For example, an example of a state where the irregularities <NUM> in the region C of <FIG> are irregularities due to the recesses of the rigid plate <NUM> and the irregularities are generated in the laminate <NUM> due to the irregularities <NUM> of the rigid plate <NUM> is shown. As shown in the region C of <FIG>, there is a case where the irregularities are generated in the radiation-shielding layer <NUM> due to the irregularities <NUM> of the rigid plate <NUM> and the irregularities 96C are generated in the sensor substrate <NUM> as the influence of the irregularities generated due to the rigid plate <NUM> propagate.

In this way, as shown in <FIG>, the base material <NUM> of the sensor substrate <NUM> is relatively easily deflected. Therefore, for example, in a case where t may be softer than the other layers (members) forming the radiation detector 10X, there is a case where the influence of irregularities caused by the radiographic imaging apparatus 1X such as the laminate <NUM> or the housing <NUM> are propagated and the irregularities are generated in the sensor substrate <NUM>. In particular, in a case where pressure, impact, or the like is applied to the top plate 120A of the housing <NUM>, such as in a case where a load of the subject is applied, the influence of the irregularities are likely to propagate to the sensor substrate <NUM>, and the irregularities are likely to be generated in the sensor substrate <NUM>. There is a case where the irregularities generated in the sensor substrate <NUM> appear as image unevenness in a radiographic image obtained by the radiation detector 10X.

In contrast, the absorption layer <NUM> of the present embodiment is provided on the side of the laminate <NUM> opposite to the side where the radiation R is radiated, and in the radiation detector <NUM> of the present embodiment, on the conversion layer <NUM> as shown in <FIG>. As described above, the absorption layer <NUM> has a function of absorbing the influence of the irregularities caused by the laminate <NUM>, the housing <NUM>, or the like and suppressing the influence of the irregularities from being propagated to the sensor substrate <NUM>.

The absorption layer <NUM> is a layer made of a soft material for absorbing the influence of the irregularities and has a durometer hardness smaller than the durometer hardness of the entire laminate <NUM>. In addition, a hardness measuring method in the present embodiment is obtained by setting a sample in a type E durometer conforming to JIS K6253 and performing a measurement <NUM> seconds after the contact of a push needle.

Specific materials for the absorption layer <NUM> include foams such as urethane foam, polyethylene, rubber sponge, and silicon foam, urethane gel, and the like.

In the radiographic imaging apparatus <NUM> (radiation detector <NUM>) of the present embodiment, as shown in <FIG>, by providing the absorption layer <NUM>, the absorption layer <NUM> is deformed in accordance with the irregularities of the columnar crystal 14A even in the region A including the irregularities of the columnar crystals 14A of the conversion layer <NUM>. Accordingly, the irregularities are not propagated to the sensor substrate <NUM>.

Additionally, as shown in <FIG>, by providing the absorption layer <NUM>, the absorption layer <NUM> is deformed in accordance with the bubbles <NUM> even in the region B where the bubbles <NUM> are generated by the radiation-shielding layer <NUM>. Accordingly, the irregularities caused by the bubbles <NUM> are not propagated to the sensor substrate <NUM>.

Moreover, as shown in <FIG>, by providing the absorption layer <NUM>, the absorption layer <NUM> is deformed in accordance with the irregularities <NUM> even in the region C where the irregularities <NUM> of the rigid plate <NUM> are generated. Accordingly, the irregularities caused by the irregularities <NUM> are not propagated to the sensor substrate <NUM>.

In this way, according to the radiation detector <NUM> of the present embodiment, the absorption layer <NUM> has the shape according to the irregularities generated in the conversion layer <NUM> of the laminate <NUM> due to the irregularities of the laminate <NUM> of the radiation detector <NUM>, the housing <NUM>, or the like. Therefore, the propagation of the irregularities to the sensor substrate <NUM> can be suppressed.

As shown in <FIG>, the absorption layer <NUM> of the present embodiment has the same size (area) as the first surface 11A side of the base material <NUM> in the sensor substrate <NUM>. The size of the absorption layer <NUM> is not limited to the form shown in <FIG> but is preferably larger than that of the sensor substrate <NUM> and preferably has at least an area larger than that of the conversion layer <NUM>.

The thickness of the absorption layer <NUM> (the thickness in the lamination direction P) is determined in accordance with a size assumed as the size of the irregularities caused by the laminate <NUM> or the housing <NUM>, for example, the bubbles <NUM> or the irregularities <NUM> shown in <FIG>. The absorption layer <NUM> preferably has at least a thickness larger than the size of the bubbles <NUM> or the irregularities <NUM>.

In addition, the absorption layer <NUM> preferably has an antistatic function for preventing the sensor substrate <NUM> from being charged, or has conductivity, and preferably has a surface resistance value of <NUM><NUM>Ω or less. As the absorption layer <NUM> having conductivity, for example, a material in which conductive carbon is kneaded into a polyethylene resin can be applied.

Additionally, the reinforcing substrate <NUM> has a function of dispersing a compressive force applied to the absorption layer <NUM> in an in-plane direction of the absorption layer <NUM>, and disperses the compressive force applied to the absorption layer <NUM>, thereby uniformly compressing the absorption layer <NUM>.

The reinforcing substrate <NUM> preferably uses a material having a bending elastic modulus of <NUM> MPa or more and <NUM>,<NUM> MPa or less. A method of measuring the bending elastic modulus is based on, for example, JIS K <NUM>:<NUM> Standard. The reinforcing substrate <NUM> preferably has a higher bending stiffness than the base material <NUM> from the viewpoint of dispersing the compressive force applied to the absorption layer <NUM> in the in-plane direction of the absorption layer <NUM>. In addition, in a case where the bending elastic modulus becomes low, the bending stiffness also becomes low. In order to obtain a desired bending stiffness, the thickness of the reinforcing substrate <NUM> should be made large, and the thickness of the entire radiation detector <NUM> increases. Considering the material of the reinforcing substrate <NUM>, the thickness of the reinforcing substrate <NUM> tends to be relatively large in a case where a bending stiffness exceeding <NUM>,<NUM> Pacm<NUM> is to be obtained. For that reason, in view of obtaining appropriate stiffness and considering the thickness of the entire radiation detector <NUM>, the material used for the reinforcing substrate <NUM> preferably has a bending elastic modulus of <NUM> MPa or more and <NUM>,<NUM> MPa or less. Additionally, the bending stiffness of the reinforcing substrate <NUM> is preferably <NUM> Pacm<NUM> or more and <NUM>,<NUM> Pacm<NUM> or less.

The reinforcing substrate <NUM> of the present embodiment is a substrate having plastic as a material. In a case where the plastic used as the material for the reinforcing substrate <NUM> is preferably a thermoplastic resin, and include at least one of polycarbonate (PC), PET, styrol, acrylic, polyacetase, nylon, polypropylene, acrylonitrile butadiene styrene (ABS), engineering plastics, or polyphenylene ether. In addition, the reinforcing substrate <NUM> is more preferably at least one of polypropylene, ABS, engineering plastics, PET, or polyphenylene ether among these, is more preferably at least one of styrol, acrylics, polyacetase, or nylon, and is more preferably at least one of PC or PET.

Additionally, the radiation-shielding layer <NUM> provided on the reinforcing substrate <NUM> has a function of shielding the radiation R transmitted through the laminate <NUM> and suppressing the radiation R transmitted to the outside of the housing <NUM>. Examples of the radiation-shielding layer <NUM> include a plate such as lead.

Moreover, the rigid plate <NUM> provided on the radiation-shielding layer <NUM> supports the radiation detector <NUM>. The rigid plate <NUM> has a higher stiffness than the sensor substrate <NUM>, and for example, carbon or the like is used.

The housing <NUM> shown in <FIG>, which houses the radiation detector <NUM> of the present embodiment, is preferably lightweight, has a low absorbance of radiation R, particularly X-rays, and has a high stiffness, and is preferably made of a material having a sufficiently high elastic modulus. As the material of the housing <NUM>, it is preferable to use a material having a bending elastic modulus of <NUM>,<NUM> MPa or more. As the material of the housing <NUM>, carbon or carbon fiber reinforced plastics (CFRP) having a bending elastic modulus of about <NUM>,<NUM> to <NUM>,<NUM> MPa can be suitably used.

In the capturing of a radiographic image by the radiographic imaging apparatus <NUM>, a load from a subject is applied to the top plate 120A of the housing <NUM>. In a case where the stiffness of the housing <NUM> is insufficient, there are concerns that problems may occur such that the sensor substrate <NUM> is deflected due to the load from the subject and the pixels <NUM> are damaged. By accommodating the radiation detector <NUM> inside the housing <NUM> consisting of a material having a bending elastic modulus of <NUM>,<NUM> MPa or more, it is possible to suppress the deflection of the sensor substrate <NUM> due to the load from the subject.

As shown in <FIG>, the radiation detector <NUM>, the power source unit <NUM>, and a control substrate <NUM> are provided side by side in a direction intersecting an incidence direction of radiation R within the housing <NUM>.

The control substrate <NUM> is a substrate in which an image memory <NUM> for storing image data according to the electric charges read from the pixels <NUM> of the sensor substrate <NUM>, a control unit <NUM> for controlling reading or the like of the electric charges from the pixels <NUM>, and the like are formed, and is electrically connected to the pixels <NUM> of the sensor substrate <NUM> by a flexible cable <NUM> including a plurality of signal wiring lines. In addition, in the radiographic imaging apparatus <NUM> illustrated in <FIG> the control substrate <NUM> is a so-called chip on film (COF) in which a drive unit <NUM> for controlling the switching states of the TFTs <NUM> of the pixels <NUM> under the control of the control unit <NUM>, and a signal processing unit <NUM> for creating and outputting image data according to the electric charges read from the pixels <NUM> are provided on the flexible cable <NUM>. However, at least one of the drive unit <NUM> or the signal processing unit <NUM> may be formed in the control substrate <NUM>.

Additionally, the control substrate <NUM> is connected to the power source unit <NUM>, which supplies electrical power to the image memory <NUM>, the control unit <NUM>, and the like that are formed in the control substrate <NUM>, by a power source line <NUM>.

In addition, as shown in <FIG>, there are many cases where each of the power source unit <NUM> and the control substrate <NUM> is thicker than the radiation detector <NUM>. In such a case, as in the example shown in <FIG>, the thickness of the portion of the housing <NUM> in which the radiation detector <NUM> is provided may be smaller than the thickness of the portion of the housing <NUM> in which each of the power source unit <NUM> and the control substrate <NUM> is provided. In addition, in this way, in a case where the thickness of the portion of the housing <NUM> in which each of the power source unit <NUM> and the control substrate <NUM> is provided and the thickness of the portion of the housing <NUM> in which the radiation detector <NUM> is provided are made different, and in a case where a step is generated at a boundary part between the two portions, there is a concern that a sense of discomfort may be given to a subject who comes into contact with a boundary part 120B. Therefore, the form of the boundary part 120B is preferably in a state of having an inclination.

Accordingly, it is possible to construct an ultra-thin portable electronic cassette according to the thickness of the radiation detector <NUM>.

Additionally, for example, in this case, the materials of the housing <NUM> may be different in the portion of the housing <NUM> in which each of the power source unit <NUM> and the control substrate <NUM> is provided and the portion of the housing <NUM> in which the radiation detector <NUM> is provided. Moreover, for example, the portion of the housing <NUM> in which each of the power source unit <NUM> and the control substrate <NUM> is provided and the portion of the housing <NUM> in which the radiation detector <NUM> is provided may be separated configured.

Additionally, in the radiographic imaging apparatus <NUM>, as in the example shown in <FIG>, the radiation detector <NUM>, the control substrate <NUM>, and the power source unit <NUM> may be housed in the housing <NUM> in a line in order from the top plate 120A side to which the radiation R is radiated.

As described above, the radiation detector <NUM> of the present embodiment includes the sensor substrate <NUM> in which the plurality of pixels <NUM> for accumulating the electric charge charges generated in response to the light converted from the radiation R are formed in the pixel region <NUM> of the flexible base material <NUM>, the conversion layer <NUM> that is provided on the first surface 11A provided with the pixel region <NUM> of the base material <NUM> and converts the radiation R into light, the absorption layer <NUM> that is provided on the side opposite to the side to which the radiation R is radiated in the laminate <NUM> in which the sensor substrate <NUM> and the conversion layer <NUM> are laminated and absorbs the influence of the irregularities generated on the conversion layer <NUM> on the sensor substrate <NUM>, and the rigid plate <NUM> that is provided on the side opposite to the side of the absorption layer <NUM> facing the laminate <NUM> and has a higher stiffness than the sensor substrate <NUM>.

As described above, according to the radiation detector <NUM> of the present embodiment, the absorption layer <NUM> has the shape according to the irregularities generated in the conversion layer <NUM> of the laminate <NUM> due to the irregularities of the laminate <NUM> of the radiation detector <NUM>, the housing <NUM>, or the like. Therefore, the influence of the irregularities on the sensor substrate <NUM> can be suppressed. Therefore, by suppressing the generation of the irregularities on the sensor substrate <NUM>, according to the radiation detector <NUM> of the present embodiment, the image unevenness or the like of the radiographic image caused by the irregularities of the sensor substrate <NUM> can be suppressed, and the quality of the radiographic image can be improved.

In addition, the position where the reinforcing substrate <NUM> is provided is not limited to the position shown in the present embodiment (refer to <FIG>), and as shown in <FIG>, the reinforcing substrate <NUM> may be provided at a position on the opposite side of the laminate <NUM>, specifically, on the side of the antistatic layer <NUM> and the protective layer <NUM>. In this case, the present invention is not limited to the example shown in <FIG>, and for example, a form may be adopted in which the reinforcing substrate <NUM> may be provided between the antistatic layer <NUM> and the sensor substrate <NUM>. This embodiments is, however, not according to the claimed invention.

Additionally, although the ISS type radiation detector <NUM> (radiographic imaging apparatus <NUM>) has been described above, as shown in <FIG>, the radiation detector <NUM> (radiographic imaging apparatus <NUM>) may be a penetration side sampling (PSS) type radiation detector <NUM> (radiographic imaging apparatus <NUM>) in which the radiation R is radiated from the conversion layer <NUM> side. Also in the radiation detector <NUM> shown in <FIG>, the absorption layer <NUM> that absorbs the influence of the irregularities generated on the conversion layer <NUM> on the sensor substrate <NUM> may be provided on the side opposite to the side on which the radiation R is radiated in the laminate <NUM> in which the sensor substrate <NUM> and the conversion layer <NUM> are laminated. Additionally, the rigid plate <NUM>, which is provided on the side opposite to the side of the absorption layer <NUM> facing the laminate <NUM> and has a higher stiffness than the sensor substrate <NUM>, is provided.

Also in the radiation detector <NUM> shown in <FIG>, the absorption layer <NUM> has the shape according to the irregularities generated in the conversion layer <NUM> of the laminate <NUM> due to the irregularities of the laminate <NUM> of the radiation detector <NUM> or the housing <NUM> and the like. Therefore, the influence of the irregularities on the sensor substrate <NUM> can be suppressed. Therefore, by suppressing the generation of the irregularities on the sensor substrate <NUM>, according to the radiation detector <NUM> of the present embodiment, the image unevenness or the like of the radiographic image caused by the irregularities of the sensor substrate <NUM> can be suppressed, and the quality of the radiographic image can be improved.

Additionally, in the above embodiments, as shown in <FIG>, an aspect in which the pixels <NUM> are two-dimensionally arranged on a matrix has been described. However, the invention is not limited to the aspect, and for example, the pixels <NUM> may be one-dimensionally arranged or may be arranged in a honeycomb shape. Additionally, the shape of the pixels is also not limited, and may be a rectangular shape, or may be a polygonal shape, such as a hexagonal shape. Moreover, the shape of the pixel region <NUM> is also not limited.

Additionally, the shape or the like of the conversion layer <NUM> is not limited to the above embodiments. In the above embodiments, an aspect in which the shape of the conversion layer <NUM> is a rectangular shape similarly to the shape of the pixel region <NUM> has been described. However, the shape of the conversion layer <NUM> may not be the same shape as the pixel region <NUM>. Additionally, the shape of the pixel region <NUM> may not be a rectangular shape but may be, for example, other polygonal shapes or a circular shape.

In addition, in the above embodiments, as an example, a form in which the conversion layer <NUM> of the radiation detector <NUM> is the scintillator including CsI has been described. However, the conversion layer <NUM> may be a scintillator in which GOS (Gd<NUM>O<NUM>S:Tb) or the like is dispersed in a binder, such as resin. The conversion layer <NUM> using GOS is formed, for example, by directly applying the binder having the GOS dispersed therein onto the sensor substrate <NUM>, the peeling layer, and the like and then drying and solidifying the binder. As a method of forming the conversion layer <NUM>, for example, a Giza method of applying an application liquid to a region where the conversion layer <NUM> is formed while controlling the thickness of an applied film may be adopted. In addition, in this case, surface treatment for activating the surface of the pixel region <NUM> may be performed before the binder having the GOS dispersed therein is applied. Additionally, an interlayer insulating film may be provided as a surface protective film on the surface of the pixel region <NUM>.

In addition, it goes without saying that the configurations of the radiographic imaging apparatuses <NUM> and the radiation detectors <NUM> that are described in the above embodiments are merely examples, and can be changed in response to situations without departing from the scope of the present invention.

Claim 1:
A radiographic imaging apparatus (<NUM>, 10X) comprising:
a sensor substrate (<NUM>) in which a plurality of pixels for accumulating electric charges generated in response to light converted from radiation is formed in a pixel region of a flexible base material (<NUM>);
a conversion layer (<NUM>) that is provided on a surface of the base material (<NUM>) provided with the pixel region and converts the radiation into light; and
an absorption layer (<NUM>) provided on the side of the conversion layer (<NUM>) opposite to the sensor substrate (<NUM>), the absorption layer (<NUM>) being
provided on a side opposite to a side to which the radiation is radiated in a laminate (<NUM>) in which the sensor substrate (<NUM>) and the conversion layer (<NUM>) are laminated and absorbs influence of irregularities generated on the conversion layer (<NUM>) on the sensor substrate (<NUM>);
a rigid plate (<NUM>) that is provided on a side of the absorption layer (<NUM>) opposite to a side facing the laminate (<NUM>) and has a higher stiffness than the sensor substrate (<NUM>); and characterized by:
a housing (<NUM>) in which the radiographic imaging apparatus (<NUM>, 10X) is housed in order of the laminate (<NUM>), the absorption layer (<NUM>), and the rigid plate (<NUM>) from the side to which the radiation is radiated; and
a reinforcing substrate (<NUM>) that is provided between the absorption layer (<NUM>) and the laminate (<NUM>) and that disperses a compressive force applied to the absorption layer (<NUM>) in an in-plane direction of the absorption layer (<NUM>)