Patent Publication Number: US-2023152476-A1

Title: Radiation detecting device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. application Ser. No. 17/218,083, filed Mar. 30, 2021, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-073196, filed Apr. 16, 2020, the entire contents of both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Technological Field 
     The present disclosure relates to a radiation detecting device. 
     Description of Related Art 
     There is known a radiation detecting device that includes a substrate and semiconductor elements formed on the imaging surface of the substrate. 
     The substrate of the known radiation detecting device is mainly made of glass. In imaging a subject, the radiation detecting device may be placed under the subject lying on the bed, and the subject may be irradiated from above. The radiation detecting device may bend owing to the weight of the subject, and the substrate in the radiation detecting device may be broken. 
     The substrate may also be broken when the radiation detecting device receives an impact by being hit or dropped accidentally while being carried. 
     To make the substrate more resistant to damage when the radiation detecting device is pressed or hit, structures to support the substrate have been developed. 
     For example, JP2019-196944A discloses a radiation imaging apparatus that includes a sensor panel, a supporter that supports the sensor panel, and a casing that houses the sensor panel and the supporter. The supporter has a vacant space and supports the lower surface of the sensor panel without a gap in the thickness direction and in the surface direction. 
     Further, according to a radiation imaging apparatus disclosed in JP2015-200606A, a housing of the radiation imaging apparatus has a supporting surface to support a radiation detection panel. The supporting surface is included in an inner surface of the bottom of the housing on a side of the radiation detection panel. On a side of the bottom opposite the side of the radiation detection panel, a concave portion is formed. The concave portion is defined by part of the outer surface of the bottom of the housing, and an electrical component is arranged in the concave portion. 
     SUMMARY 
     According to the known radiation detecting device disclosed in JP2019-196944A and JP2015-200606A, however, the supporter needs to have a certain degree of rigidity or greater to support and protect the glass substrate against loads and impacts. 
     To ensure the rigidity of the supporter, the supporter needs to be thick, or at least part of the supporter (e.g., surface layer part) needs to be made of a material having a high degree of rigidity, such as fiber reinforced resin or metal. 
     Ensuring the rigidity of the supporter as described above increases the weight of the supporter, thereby increasing the weight of the radiation detection device. 
     The substrate made of glass, which is a relatively heavy material, makes the radiation detecting device further heavier. 
     The present disclosure has been made in view of the above issues. Objects of the present disclosure include reducing the weight of a radiation detecting device that includes a substrate and semiconductor elements formed on the surface of the substrate while keeping the substrate resistant against loads and impacts. 
     To achieve at least one of the abovementioned objects, according to an aspect of the present disclosure, there is provided a radiation detecting device, including: a radiation detector that includes a flexible substrate and a semiconductor element formed on an imaging surface of the substrate; and a supporter that is formed of foam and that supports the radiation detector. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, wherein: 
         FIG.  1    is a perspective view of a radiation detecting device according to first and second embodiments of the present invention; 
         FIG.  2    is an A-A cross-sectional view of the radiation detecting device in  FIG.  1    in the first embodiment; 
         FIG.  3    is a cross-sectional view of part of  FIG.  2   ; 
         FIG.  4    is a plan view of part of the radiation detecting device (light-electricity converter) in  FIG.  1    as an example; 
         FIGS.  5 A and  5 B  are lateral views of a supporter of the radiation detecting device in  FIG.  1    as an example; 
         FIG.  6    is a lateral view of the radiation detecting device in  FIG.  1    in the production process; 
         FIG.  7    is a perspective view of the radiation detecting device in  FIG.  1    in the production process; 
         FIG.  8 A  is a perspective view of an attaching member as an example; 
         FIG.  8 B  is a cross-sectional view of the attaching member in  FIG.  8 A  fixed to the supporter; 
         FIG.  9 A  is a perspective view of the attaching member as an example; 
         FIG.  9 B  is a cross-sectional view of the attaching member in  FIG.  9 A  fixed to the supporter; 
         FIG.  10 A  is a perspective view of the attaching member as an example; 
         FIGS.  10 B to  10 D  are cross-sectional views of the attaching member in  FIG.  10 A  fixed to the supporter; 
         FIG.  11    is a perspective view of the attaching member as an example; and 
         FIG.  12    is an A-A cross-sectional view of the radiation detecting device in  FIG.  1    in the second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the disclosed embodiments. 
     First Embodiment 
     A first embodiment of the present invention is described. 
     A schematic configuration of a radiation detecting device in this embodiment (hereinafter called a detecting device  100 ) is described. 
       FIG.  1    is a perspective view of the detecting device  100 .  FIG.  2    is an A-A cross-sectional view of the detecting device  100 .  FIG.  3    is a cross-sectional view of part of  FIG.  2    (part shown in III in  FIG.  2   ).  FIG.  4    is a plan view of part of the detecting device  100  (light-electricity converter).  FIGS.  5 A and  5 B  are lateral views of a supporter included in the detecting device  100  as an example.  FIG.  6    is a lateral view of the detecting device  100  in the production process.  FIG.  7    is a perspective view of the detecting device  100  in the production process.  FIGS.  8 A,  9 A,  10 A  are perspective views of examples of an attaching member.  FIGS.  8 B,  9 B,  10 B,  10 C,  10 D  are cross-sectional views of the respective attaching members in  FIGS.  8 A,  9 A,  10 A  fixed to the supporter.  FIG.  11    is a perspective view of an example of the attaching member. 
     Reference numerals in parentheses in the figures are for the second embodiment to be described later. 
     The detecting device  100  is for generating a radiographic image in response to receiving radiation. 
     The detecting device  100  includes, for example, a casing  110  and an internal module  120 , as shown in  FIG.  1   . 
     In this embodiment, the detecting device  100  further includes various switches S, such as a power supply switch and control switch, and an indicator I. 
     [1. Casing] 
     The casing  110  houses the internal module  120 . 
     The casing  110  includes a box body  1  and a lid body  2 , as shown in  FIG.  2   . 
     The casing  110  in this embodiment has a shape of a rectangular panel. 
     [1-1. Box Body] 
     The box body  1  in this embodiment includes a front part  11  and a lateral part  12  that are formed integrally. 
     The front part  11  and the lateral part  12  may be different members. 
     (1-1-1. Front Part) 
     The front part  11  faces an imaging surface  312   g  included in the internal module  120 , which is described later, and spreads in parallel with the imaging surface  312   g.    
     The outer surface of the front part  11  is a radiation entrance surface  11   a  of the detecting device  100  (the front surface of the casing  110 ). 
     The front part  11  in this embodiment is formed to be a rectangular plate. 
     On the radiation entrance surface  11   a  in this embodiment, an effective image region of a sensor panel  31  is shown with a frame (not illustrated). The effective image region is a region in which semiconductor elements  312   b  are arranged. 
     The front part  11  is made of a material that allows radiation to pass through. 
     The casing  110  in this embodiment is made of carbon fiber reinforced plastic/resin (CFRP), glass fiber reinforced plastic/resin (GFRP), light metal, or light metal-containing alloy. 
     The casing  110  may be made of carbon fiber reinforced thermoplastic (CFRTP) resin. 
     When the material of the casing  110  is CFRP, CFRTP, or GFRP, the casing  110  may be formed of a sheet molding compound (SMC). The SMC is a material that includes fibers shorter than fibers of a prepreg. 
     Examples of the light metal include aluminum and magnesium that have a relatively small density. 
     Using the above-described materials can reduce the weight of the casing  110  while keeping the rigidity of the casing  110 . 
     The CFRP in particular has a high radiation transmissivity and allows radiation that has passed through a subject to reach the internal module  120  without decrease. Making the casing  110  of CFRP therefore improves the image quality of the radiographic image than making the casing  110  of other materials. 
     (1-1-2. Lateral Part) 
     The lateral part  12  extends from the edge portions of the front part  11  towards a rear part  21  in a direction orthogonal to the radiation entrance surface  11   a.    
     The outer surface of the lateral part  12  is the lateral surface of the detecting device  100  (casing  110 ). 
     [1-2. Lid Body] 
     The lid body  2  includes the rear part  21 . 
     In this embodiment, the whole lid body  2  constitutes the rear part  21 . 
     The rear part  21  faces the front part  11  of the box body  1  with the internal module  120  inbetween and spreads in parallel with the front part  11 . 
     The outer surface of the rear part  21  is the rear surface of the detecting device  100  (casing  110 ). 
     The rear part  21  in this embodiment is formed to have substantially the same rectangle shape as the front part  11 . 
     The rear part  21  in this embodiment is made of CFRP, GFRP, light metal, or light metal-containing alloy. 
     The material of the rear part  21  may be the same as or different from the material of the box body  1 . 
     The lid body  2  (rear part  21 ) abuts the lateral part  12  of the box body  1  and is attached to the lateral part  12 . 
     The lateral part  12  thus connects the front part  11  and the rear part  21 . 
     In this embodiment, the lid body  2  is screwed on the box body  1 . 
     In repairing or doing maintenance of the detecting device  100 , the rear part  21  can be separated from the front part  11  and the lateral part  12  by loosening and removing screws. A person who does maintenance of the detecting device  100  can therefore easily access the internal module  120 , which is housed in the front part  11  and the lateral part  12 . 
     To make the casing  110  watertight, the box body  1  and the lid body  2  may be fixed to each other with screws with a gasket inbetween or may be adhered to each other. The watertight casing  110  can prevent foam from absorbing water and affecting the sensor panel and electrical components. 
     [1-3. Others] 
     The front part  11  and the lateral part  12  of the casing  110  (box body  1 ) are formed integrally in  FIG.  1   . 
     Instead, the lateral part  12  and the rear part  21  of the casing  110  may be formed integrally. Further, the front part  11 , the lateral part  12 , and the rear part  21  may be different members. 
     Both the front part  11  and the rear part  21  may include a lateral part. 
     Further, although the casing  110  in  FIG.  1    includes the box body  1  and the lid body  2 , the casing  110  may include a tubular body and a lid body. The tubular body has the front part  11 , the rear part  21 , and a pair of lateral parts  12  that connect the edges of the front part  11  and the edges of the rear part  21 . The lid body covers the opening of the tubular body. 
     The casing  110  may have recess portions at the edge portions of the rear part  21 . A person carrying the detecting device  100  can hook his/her fingers on the recess portions to hold the detecting device  100  more securely, so that the person is less likely to drop the detecting device  100 . 
     The casing  110  may be antimicrobial-treated on the entire surface, or an antimicrobial material may be kneaded in the material of the casing  110 . 
     Further, the casing  110  may be provided with protecting members on the corners (at least the four corners of the front part  11  or the four corners of the rear part  21 ). 
     The material of the protecting members may be metal or elastic body, such as resin, rubber, or elastomer because the detecting device  100  in this embodiment is light and receives a smaller impact when being hit. 
     At least one of the protecting members may have a different color and/or form from the color and/or form of the other protecting members. The protecting member having a different color and/or form allows a user to easily recognize the orientation of the detecting device  100 . 
     [2. Internal Module] 
     The Internal module  120  is fixed to at least one of the inner surface of the front part  11 , the inner surface of the rear part  21 , and the inner surface of the lateral part  12  of the casing  110 . 
     In this embodiment, the internal module  120  is fixed to the inner surface of the front part  11 , as shown in  FIG.  2   . 
     The internal module  120  may be fixed to the casing  110  by gluing with a glue, adhesion with an adhesive tape, fitting a recess part to a projecting part formed on inner surfaces, or engaging with engaging parts formed on inner surfaces. 
     Fixing the internal module  120  can prevent the internal module  120  from moving when the detecting device  100  receives an impact in a direction substantially orthogonal to the lateral surface of the detecting device  100 . 
     The internal module  120  may be fixed to the inner surface of the rear part  21  or the inner surface of the lateral part  12 . 
     The internal module  120  may be fixed to the inner surfaces of the front part  11  and the rear part  21 , or the inner surfaces of the front part  11  and the lateral part  12 , or the inner surfaces of the lateral part  12  and the rear part  21 . 
     The internal module  120  may be fixed to the inner surfaces of the front part  11 , the lateral part  12 , and the rear part  21 . 
     The internal module  120  in this embodiment is separate from the inner surface of the lateral part  12  by a distance d 1 . That is, a gap having the width of d 1  or greater is present between the internal module  120  and the lateral part  12 . 
     The gap can prevent the internal module  120  from bumping into the lateral part  12  of the detecting device  100  and being broken when the detecting device  100  receives an impact in a direction substantially orthogonal to the lateral surface of the detecting device  100 . 
     The internal module  120  includes a radiation detector  3  and a supporter  4 . 
     The internal module  120  in this embodiment further includes an electrical component  5 . 
     [2-1. Radiation Detector] 
     The radiation detector  3  is placed between the front part  11  of the casing  110  and the supporter  4 . 
     In this embodiment, the radiation detector  3  is placed between the front part  11  of the casing  110  and the supporter  4  via adhesive layers  6 . 
     The radiation detector  3  includes the sensor panel  31 , as shown in  FIG.  3   . 
     The radiation detector  3  in this embodiment further includes a radiation shielding layer  32 , an electromagnetic-field shielding layer  33 , and a cushioning material  34 . 
     (2-1-1. Sensor Panel) 
     The sensor panel  31  in this embodiment is placed between the radiation shielding layer  32  and the electromagnetic-field shielding layer  33 . 
     The sensor panel  31  includes a wavelength converter  311  and a light-electricity converter  312 . 
     The wavelength converter  311  is for converting radiation into visible lights or other lights. 
     The wavelength converter  311  in this embodiment is placed between the electromagnetic-field shielding layer  33  and the light-electricity converter  312 . 
     The wavelength converter  311  in this embodiment spreads in parallel with the radiation entrance surface  11   a  of the casing  110 . 
     The wavelength converter  311  in this embodiment includes a supporting layer and a phosphor layer, which are not illustrated. 
     The supporting layer is made of flexible material in a film shape (thin plate). 
     Examples of the flexible material include polyethylene naphthalate, polyethylene terephthalate (PET), polycarbonate, polyimide, polyamide, polyetherimide, aramid, polysulfone, polyether sulfone, fluororesin, polytetrafluoroethylene (PTFE), and composite material that is a mixture of at least two materials among the above materials. 
     Polyimide, polyamide, polyetherimide, PTFE, or composite material of these materials are particularly preferable among the above materials for improving heat resistance. 
     The supporting layer in this embodiment is formed to be rectangular. 
     The phosphor layer is formed of a phosphor on the surface of the supporting layer. 
     The phosphor is a substance that glows as a result of excitation of atoms when being irradiated with ionizing radiation, such as α-rays, γ-rays, and X-rays. The phosphor converts radiation into ultraviolet rays or visible lights. 
     As the phosphor, column crystals of cesium iodide (CsI) can be used, for example. 
     The phosphor layer in this embodiment is formed on the whole surface of the supporting layer that faces the light-electricity converter  312 . 
     That is, the wavelength converter  311  is formed to be rectangular. 
     The thickness of the phosphor layer in this embodiment is set such that the phosphor layer can bend (deform elastically) when the supporting layer bends. 
     The wavelength converter  311  formed as described above is a flexible plate. When the wavelength converter  311  is irradiated, the irradiated region glows at an intensity corresponding to the dose of received radiation. 
     The light-electricity converter  312  is for converting light into electric signals. 
     The light-electricity converter  312  in this embodiment is placed between the wavelength converter  311  and the radiation shielding layer  32 . 
     The light-electricity converter  312  in this embodiment is placed so as to spread in parallel with the wavelength converter  311 . 
     The light-electricity converter  312  is adhered to the wavelength converter  311 . 
     The light-electricity converter  312  includes a substrate  312   a  and multiple semiconductor elements  312   b,  as shown in  FIG.  4   . 
     The light-electricity converter  312  in this embodiment includes scanning lines  312   c,  signal lines  312   d,  switch elements  312   e,  and bias lines  312   f.    
     The substrate  312   a  is made of a flexible material in a film shape (thin plate). 
     The substrate  312   a  in this embodiment has substantially the same rectangular shape as the wavelength converter  311  when viewed from the front. 
     The substrate  312   a  in this embodiment is made of the same material as the supporting layer of the wavelength converter  311 . 
     More specifically, the substrate  312   a  in this embodiment has flexibility, and the thermal expansion coefficient and the thermal contraction coefficient of the substrate  312   a  are the same as the thermal expansion coefficient and the thermal contraction coefficient of the supporting layer. 
     Because the light-electricity converter  312  and the wavelength converter  311  together expand with heat, the laminate of the light-electricity converter  312  and the wavelength converter  311  is less likely to warp. As a result, a glowing part of the wavelength converter  311  is less likely to shift from the position of the semiconductor element  312   b  that faces the glowing part. This can prevent decrease in quality of radiographic images. 
     The substrate  312   a  may be made of material that is different from the material of the supporting layer and that has the same thermal expansion coefficient and thermal contraction coefficient as those of the supporting layer. 
     The semiconductor elements  312   b  generate electric charges corresponding to the intensity of received lights. 
     The semiconductor elements  312   b  are arranged two-dimensionally on the surface of the substrate  312   a.    
     More specifically, the semiconductor elements  312   b  are arranged in a matrix on the surface of the substrate  312   a  that abuts (that is adhered to) the wavelength converter  311 . 
     The semiconductor elements  312   b  in this embodiment are arranged in a matrix at the central part of the imaging surface  312   g.  More specifically, on the surface of the substrate  312   a,  the scanning lines  312   c  (not illustrated) are formed so as to extend in parallel with each other at regular intervals, and the signal lines  312   d  (not illustrated) are formed at regular intervals so as to orthogonally cross the scanning lines  312   c.  The semiconductor elements  312   b  are arranged in the respective rectangular regions defined by the scanning lines  312   c  and the signal lines  312   d.  The rectangular regions correspond to pixels in a radiographic image. 
     Each of the rectangular regions also includes a switch element  312   e.  The switch element  312   e  consists of a thin film transistor (TFT), for example. The gate of the switch element  312   e  is connected to the scanning line  312   c.  The source of the switch element  312   e  is connected to the signal line  312   d.  The drain of the switch element  312   e  is connected to the semiconductor element  312   b.    
     The surface of the substrate  312   a  on which the semiconductor elements  312   b  are formed is hereinafter called an imaging surface  312   g.    
     The light-electricity converter  312  formed as described above is flexible and placed such that the imaging surface  312   g,  on which the semiconductor elements  312   b  are formed, faces the wavelength converter  311 . 
     (2-1-2. Radiation Shielding Layer) 
     The radiation shielding layer  32  is for preventing scattered radiation from reaching the electric circuits  51 . 
     The radiation shielding layer  32  in this embodiment is placed between the sensor panel  31  (light-electricity converter  312 ) and the electromagnetic-field shielding layer  33 , as shown in  FIG.  3   . 
     The radiation shielding layer  32  in this embodiment fixes the sensor panel  31  with an attaching part (not illustrated). 
     (2-1-3. Electromagnetic-Field Shielding Layer  33 ) 
     The electromagnetic-field shielding layer  33  is for shielding noises. 
     The electromagnetic-field shielding layer  33  is provided at a side where the imaging surface  312   g  of the radiation detector  3  is provided (imaging surface-side) and/or the opposite side from the imaging surface-side. 
     In this embodiment, the electromagnetic-field shielding layer  33  is provided at the imaging surface-side and the opposite side from the imaging surface-side. 
     The electromagnetic-field shielding layer  33  provided at the opposite side from the imaging surface-side may be adhered to the supporter  4 . 
     The electromagnetic-field shielding layer  33  is a laminate. Part of the electromagnetic-field shielding layer  33  includes a conductive material. 
     The electromagnetic-field shielding layer  33  in this embodiment may be a resin film on which a metal layer is formed, or a film made of a transparent conductive material, such as indium tin oxide (ITO). 
     The metal may be aluminum or copper, for example. 
     Methods of forming the metal layer include pasting metal foils and depositing metal. 
     As the electromagnetic-field shielding layer  33 , a film, such as the AL-PET (registered trademark of Panac Co., Ltd.) is suitable. 
     At least one layer of the electromagnetic-field shielding layers  33  is provided at one side. 
     The electromagnetic-field shielding layer  33  provided at the imaging surface-side can shield external noises entering from the front surface side. 
     The electromagnetic-field shielding layer  33  provided at the opposite side from the imaging surface-side can shield noises generated by the electric circuits  51 . 
     The electromagnetic-field shielding layer  33  may be connected to the ground (GRD), for example. Connecting the electromagnetic-field shielding layer  33  to the ground keeps the electric potentials of the electromagnetic-field shielding layer  33  constant, thereby further improving the noise-shielding effect. 
     In the case, it is preferable to interpose a metal (e.g., nickel) the ionization tendency of which is not so different from the ionization tendency of aluminum or copper. 
     Such a metal may be interposed as a coating of an intermediate member or as a conductive filament in a conductive tape, for example. 
     When metals the ionization tendencies of which are largely different (e.g., aluminum and copper) come into contact, electrolytic corrosion may occur. Using metals the ionization tendencies of which are not so different can prevent electrolytic corrosion. 
     (2-1-4. Cushioning Material) 
     The cushioning material  34  is for absorbing external loads and impacts. 
     The cushioning material  34  in this embodiment is placed between the front part  11  of the casing  110  and the electromagnetic-field shielding layer  33 . The cushioning material  34  can therefore prevent external loads and impacts coming from the side of the front part  11  from reaching the sensor panel  31 . 
     [2-2. Supporter] 
     The Supporter  4  is for supporting the radiation detector  3 . 
     “Supporting” includes supporting the radiation detector  3  against load coming from the side of the front part  11  and supporting the radiation detector  3  placed on the supporter  4 . 
     As shown in  FIG.  2   , the supporter  4  is provided between the radiation detector  3  and the rear part  21  to disperse external loads on the casing  110 . The supporter  4  can therefore prevent the radiation detector  3  (sensor panel  31 ) from bending. 
     The supporter  4  is formed of foam. 
     Examples of the foam include polyethylene, polypropylene, polystyrene, modified-polyphenyleneether, polyurethane, acrylic, epoxy, and composite material of at least two materials among these resins. 
     Soft resin typically has a lower degree of rigidity than hard resin. On the other hand, it is known that the foam made of soft resin has a higher degree of rigidity when the expansion ratio of the foam is lower. The foam can have a desired degree of rigidity by adjusting the expansion ratio of the foam in production process. 
     It is preferable that the expansion ratio be equal to or less than 30 times. The supporter  4  can therefore keep desired rigidity without using a material the degree of rigidity of which is higher than the degree of rigidity of foam (e.g., fiber reinforced resin or metal) for part of the supporter  4  (e.g., surface layer part). Further, the supporter  4  can be light. 
     The supporter  4  may be made of resin the thermal expansion coefficient of which is the same as the thermal expansion coefficient of the sensor panel  31 , or may be made of resin the thermal expansion coefficient of which is different from the thermal expansion coefficient of the sensor panel  31  by a certain degree or less. 
     Further, the supporter  4  may have elasticity. 
     The sensor panel  31  has a greater thermal expansion coefficient than a known sensor panel that includes a glass substrate. According to the above, when the sensor panel  31  expands, the supporter  4  also expands as much as the sensor panel  31  or deforms elastically to absorb the expansion of the sensor panel  31 . This can prevent wrinkles on the sensor panel  31  that occur when only the sensor panel  31  expands. 
     The supporter  4  includes a first part  4   a  and a second part  4   b.    
     The first part  4   a  is placed without a gap along the opposite surface of the light-electricity converter  312  of the sensor panel  31  from the imaging surface  312   g.  More specifically, the first part  4   a  is placed along the surface of the electromagnetic-field shielding layer  33  or the surface of the adhesive layer  6  provided at the opposite side from the imaging surface-side, where the imaging surface  312   g  of the light-electricity converter  312  is provided. 
     The first part  4   a  has a predetermined width in the direction orthogonal to the opposite surface from the imaging surface  312   g.  The first part  4   a  has a plate shape and extends in parallel with the opposite surface from the imaging surface  312   g.  With the first part  4   a,  the supporter  4  can further disperse external loads on the casing  110  to prevent the radiation detector  3  from bending. 
     The second part  4   b  is provided between the radiation detector  3  and the rear part  21  such that no gap is present. 
     With the second part  4   b,  the supporter  4  can further disperse external loads on the casing  110  to prevent the radiation detector  3  from bending. 
     The supporter  4  also has a recess part  4   c  as well as the first part  4   a  and the second part  4   b  on the surface facing the rear part  21  of the casing  110 . 
     The width, length, and depth of the recess part  4   c  are set such that the electric circuit  51  can be housed. 
     The supporter  4  in this embodiment has multiple recess parts  4   c,  or at least as many recess parts  4   c  as the number of electric circuits  51 . 
     The supporter  4  in this embodiment is divided into multiple parts, namely includes the first supporter  41  and the second supporter  42 . 
     (2-2-1. First Supporter) 
     A surface of the first supporter  41  abuts the radiation detector  3 , and the other surface of the first supporter  41  abuts the electric circuits  51 . 
     The first supporter  41  in this embodiment corresponds to the above-described first part  4   a.    
     The surface of the first supporter  41  that abuts the radiation detector  3  is flat in this embodiment, and is hereinafter called a supporting surface  41   a.    
     The supporting surface  41   a  in this embodiment is as large as the sensor panel  31  or is one size larger than the sensor panel  31 , so that the first supporter  41  can support the whole body of the sensor panel  31 . 
     It is preferable that the width of the first supporter  41  (distance between the supporting surface  41   a  and the opposite surface from the supporting surface  41   a ) be within 2 to 5 millimeters, so that the first supporter  41  has a space for housing the electric circuits  51  to be described later while keeping rigidity. 
     The first supporter  41  in this embodiment includes two types of foam that have different degrees of rigidity. 
     The first supporter  41  in this embodiment includes a first foam F 1  and a second foam F 2 . 
     The first foam F 1  constitutes the surface layer part that is in contact with the radiation detector  3  and/or the second supporter  42 . 
     The second foam F 2  constitutes the core part that is in contact with the surface layer part in a direction in which the radiation detector  3  and the second supporter  42  are arranged. 
     Accordingly, the expansion ratio of the first supporter  41  changes in a direction orthogonal to the supporting surface  41   a.    
     The expansion ratio of the first foam F 1  is less than the expansion ratio of the second foam F 2 . The degree of rigidity of the first foam F 1  is therefore higher than the degree of rigidity of the second foam F 2 . 
     The first supporter  41  described above has an improved degree of rigidity against bending, and eventually improves the rigidity of the detecting device  100  against bending. 
     Although the first supporter  41  in  FIG.  2    and  FIG.  5 A  has a uniform thickness (uniform width in the direction orthogonal to the supporting surface  41   a ), the first supporter  41  may have thicker edge portions along the supporting surface  41   a  than the central portion. Such a first supporter  41  can further improve rigidity against loads and impacts. 
     Alternatively, the central portion of the first supporter  41  may be thicker than the edge portions. 
     (2-2-2. Second Supporter) 
     A surface of the second supporter  42  is in contact with the first supporter  41 , and the other surface of the second supporter  42  is in contact with the rear part  21 , as shown in  FIG.  2   . 
     The first supporter  41  and the second supporter  42  in this embodiment are different members, as shown in  FIG.  6   . 
     The second supporter  42  in this embodiment extends towards the rear part  21  from part of the opposite surface of the first supporter  41  from the supporting surface  41   a.  The part of the opposite surface is not in contact with the electric circuits  51  to be described later. 
     Different from the first supporter  41 , the second supporter  42  is formed so as to fill part of a space along the opposite surface of the light-electricity converter  312  from the imaging surface  312   g.  More specifically, the second supporter  42  fills part of a space along the surface of the electromagnetic-field shielding layer  33  or the surface of the adhesive layer  6  provided at the opposite surface-side of the light-electricity converter  312  from the imaging surface  312   g.  The recess parts  4   c  are formed at the side of the rear part  21  in a direction along the supporting surface  41   a.    
     The second supporter  42  in this embodiment includes two types of foam that have different degrees of rigidity, as with the first supporter  41 . 
     The second supporter  42  in this embodiment includes the first foam F 1  and the second foam F 2 , as shown in  FIG.  5 A . 
     The first foam F 1  of the second supporter  42  constitutes a surface layer part that extends from the first supporter  41  towards the rear part  21 . 
     The second foam F 2  of the second supporter  42  constitutes a core part that is in contact with the surface layer part in a direction along the inner surface of the rear part  21 . 
     The expansion ratio of the second supporter  42  therefore changes in a direction along the supporting surface  41   a.  The distribution of the expansion ratio of the second supporter  42  is different from the distribution of the expansion ratio of the first supporter  41 . 
     The second supporter  42  as described above has an improved degree of rigidity against loads coming from a direction orthogonal to the supporting surface  41   a.  Accordingly, the detecting device  100  can has an improved degree of rigidity against loads coming from a direction orthogonal to the rear/front surface of the detecting device  100 . 
     (2-2-3. Supporter and Other Members) 
     In this embodiment, the directions in which the first foam F 1  and the second foam F 2  are arranged are different between the first supporter  41  and the second supporter  42 . Accordingly, the first supporter  41  and the second supporter  42  are strong in different directions. In such a case, the rigidity against loads and impacts coming from the thickness direction (direction orthogonal to the supporting surface  41   a ) may be greater than the rigidity against loads and impacts coming from the direction along the supporting surface  41   a.    
     Further, only either the first supporter  41  or the second supporter  42  may be formed of the first foam F 1  and the second foam F 2 , and the other supporter may be formed of only the first foam F 1  or the second foam F 2 . 
     Further, both the first supporter  41  and the second supporter  42  may be formed of only the first foam F 1  or the second foam F 2 . 
     Further, the first supporter  41  and the second supporter  42  of the supporter  4  may be integrally formed of a uniform piece of foam, as shown in  FIG.  5 B . 
     The recess parts  4   c  may be formed by cutting the parts where the recess parts  4   c  are supposed to be or by partly pressing the supporter  4 . It is preferable, however, that the recess part  4   c  be formed by pressing part of the supporter  4 . 
     The parts of the supporter  4  where the recess parts  4   c  are formed are thinner than the other parts of the supporter  4  (second part  4   b ). More specifically, the width of the parts where the recess parts  4   c  are formed is less than the width of the other parts of the supporter  4  in the direction orthogonal to the supporting surface  41   a.  When the recess parts  4   c  are formed by pressing part of the supporter  4 , the surfaces of the recess parts  4   c  have a lower expansion ratio and therefore have higher rigidity. The recess parts  4   c  of the supporter  4  can therefore be as rigid as the second parts  4   b.    
     The supporter  4  may be formed by laminating multiple sheets of foam. 
     [2-3. Electrical Component] 
     The electrical component  5  includes the electric circuits  51  and a wire(s)  52  shown in  FIG.  2    and a heat diffusion sheet (not illustrated). 
     The electric circuits  51  in this embodiment are attached to the supporter  4 . 
     The radiation detector  3 , the supporter  4 , and the electric circuits  51  are fixed to each other to constitute the internal module  120 . 
     (2-3-1. Electric Circuit) 
     The electric circuits  51  are positioned on the opposite surface of the supporter  4  from the supporting surface  41   a.    
     The electric circuits  51  are housed in the recess parts  4   c  of the supporter  4  between the second supporters  42 . 
     The electric circuits  51  are separate from the rear part  21  of the casing  110 , so that the electric circuits  51  can avoid receiving external loads placed on the casing  110 . 
     The electric circuits  51  include a scanning circuit, reading circuit, wireless communication circuit, control circuit, power-source circuit, battery, and connector. 
     The scanning circuit controls switch elements. 
     The reading circuit reads electric charges as signals. 
     The wireless communication circuit is for wirelessly communicating with other devices. 
     The control circuit controls the circuits to generate image data. 
     The power-source circuit is for applying voltage to semiconductor elements and supplying electricity for the above-described circuits. 
     The connector can accept a cable for communicating with other devices, as shown in  FIG.  1   . 
     (2-3-2. Attaching Electric Circuit to Supporter) 
     The electric circuits  51  in this embodiment are attached to the supporter  4  with the attaching members  7 , as shown in  FIG.  6   . 
     Each of the attaching members  7  in this embodiment includes a plate part  71  that is in contact with the electric circuit  51  and a projecting part  72 , as shown in  FIG.  7   . 
     The first supporter  41  of the supporter  4  has a fitting hole(s)  41   b  the contour of which is the same as the contour of the projecting part  72 . 
     The projecting part  72  in this embodiment has radial parts  72   a  that spread radially from the center of the plate part  71  in the radial direction of the plate part  71 . Such a projecting part  72  has greater friction against the supporter  4  when being fitted to the supporter  4 . As a result, the attaching member  7  is less likely to detach from the supporter  4 . 
     When the attaching member  7  is screwed on the electric circuit  51 , the attaching member  7  receives torque. The radial parts  72   a  protruding in a direction orthogonal to the torque can prevent the attaching member  7  from turning as the screw turns. 
     Further, the radial parts  72   a  reduce pressure on the supporter  4  by engaging with the supporter  4  on a predetermined area or greater. Large torque can therefore be applied to the supporter  4  without damaging the foam, which has a low degree of rigidity, in screwing the electric circuit  51  on the supporter  4 . The screw can therefore be prevented from being loose. 
     The structure of the attaching member  7  is not limited to the structure described above. 
     For example, the attaching member  7  may include a first member  7   a  and a second member  7   b,  as shown in  FIG.  8 A . 
     The first member  7   a  of the attaching member  7  includes a tube part  73  and a flange part  74 . 
     The tube part  73  fits the fitting hole  41   b  formed on the first supporter  41 . 
     The flange part  74  abuts the supporting surface  41   a  of the supporter  4 . 
     The second member  7   b  includes an internal-screw part  75  and a flange part  76 . 
     The second member  7   b  may be made of the same foam as the supporter  4 . The internal-screw part  75  fits the tube part  73 . 
     In the central part of the internal-screw part  75 , an insert screw  75   a  is inserted. Alternatively, an internal screw may be directly formed on the internal-screw part  75 . 
     The flange part  76  abuts the supporting surface  41   a  of the first supporter  41 . The attaching member  7  sandwiches the supporter  4  between the flange part  74  and the flange part  76 . 
     When the second member  7   b  is made of foam, the second member  7   b  can be connected to the supporter  4  with the heat generated in forming the supporter  4 . 
     The internal-screw part  75  accepts a screw B through the screw hole  51   a  of the electric circuit  51 , so that the electric circuit  51  is fixed to the supporter  4 . 
     A ground wire(s) of the electric circuit  51  is extended around the screw hole  51   a.  The ground wire is fastened with the screw B along with the electric circuit  51 , thereby being connected to the ground terminal near the screw hole  51   a.    
     The attaching member  7  may include an internal-screw part  75 A and a flange part  76 A, as shown in  FIG.  9   . 
     The flange part  76 A of the attaching member  7  abuts the supporting surface  41   a  of the supporter  4 . 
     The internal-screw part  75 A fits the fitting hole  41   b  formed on the first supporter  41 . 
     The internal-screw part  75 A has a wavy outer circumferential surface. 
     The distance d 2  between the tops of the waves is equal to or greater than the diameter of a particle of the foam, so that the particles of the foam constituting the supporter  4  enter the spaces between the waves of the internal-screw part  75 A. The attaching member  7  is therefore prevented from turning along with the screw B when receiving torque from the screw B being turned to fix the electric circuit  51 . 
     Further, the attaching member  7  may include an internal-screw part  75 B and a plate part  71 A, as shown in  FIG.  10 A . 
     The internal-screw part  75 B may be cylindrical as shown in  FIG.  10   , or may have a wavy lateral circumferential surface as shown in  FIG.  9   . 
     The plate part  71 A has a connecting surface  71   a  the area of which is sufficiently wider than the width of the internal-screw part  75 . 
     The connecting surface  71   a  of the plate part  71 A is adhered to the first supporter  41 , as shown in  FIG.  10 B . 
     Instead, a surface of the plate part  71  of the attaching member  7  may be connected to the first supporter  41 , the surface being opposite from the surface on which the internal-screw part  75   b  is provided, as shown in  FIG.  10 C . 
     Further, the attaching member  7  may be connected to the radiation shielding layer  32 , as shown in  FIG.  10 D . 
     Further, the attaching member  7  may include an engaging part  77 , as shown in  FIG.  11   . 
     The engaging part  77  engages with the screw hole  51   a  formed on the electric circuit  51  by a snap-fit. 
     As the foam constituting the supporter  4  is not resistant to torque, the attaching member  7  may turn when being screwed on the electric circuit  51 . With the snap-fit, the supporter  4  can be easily engaged with and attached to the electric circuit  51 . 
     The attaching member  7  may not be used in attaching the electric circuit  51  to the supporter  4 . 
     The electric circuit  51  may be directly fixed to the supporter  4  with a glue or an adhesive tape. 
     As the electric circuit  51  is not fixed together with the wires, the connectors may be connected with wires of conductive tapes, for example. 
     (2-3-3. Wire) 
     The wires  52  are made of flexible printed circuits, for example. The wires  52  connect the light-electricity converter  312  and the electric circuits  51 . 
     More specifically, the wires  52  connect (i) the terminals of the scanning lines (switch elements) and the scanning circuit, (ii) the terminals of the signal lines (semiconductor elements  312   b ) and the reading circuit, and (iii) the terminals of the bias lines and the power-source circuit of the light-electricity converter  312 . 
     (2-3-4. Heat Diffusion Sheet) 
     The heat diffusion sheet is positioned so as to face, among elements constituting the electric circuit  51 , elements that generate heat when the electric circuit  51  is in operation. 
     The positions to face the elements include the rear surfaces of the electric circuits  51 , the supporter  4 , and the casing  110 . 
     The heat diffusion sheet diffuses heat generated by the elements to prevent overheat of the elements and decrease in functions of the elements. 
     The heat diffusion sheet also prevents occurrence of heat spots in regions facing the elements. 
     The heat diffusion sheet may face the elements with a heat transferring member inbetween. 
     Second Embodiment 
     Next, the second embodiment of the present invention is described. In the second embodiment, components that are the same as the components of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. 
       FIG.  12    is an A-A cross-sectional view of a radiation detecting device (hereinafter called detecting device  100 A) in this embodiment. 
     The structure of the casing  110 A of the detecting device  100 A in this embodiment is different from the structure of the casing  110  in the first embodiment. 
     [3. Lid Body] 
     A lid body  2 A in this embodiment includes a rear part  21 A and lids  22 . 
     [3-1. Rear Part] 
     The rear part  21 A has recess parts  21   a.    
     The recess parts  21   a  are recessed towards the inside of the casing  110 A from the outer surface of the rear part  21 A. 
     The lateral surfaces of the recess parts  21   a  have slits (not illustrated). 
     The width, length, and depth of each of the recess parts  21   a  are set such that the electric circuit  51  can be housed. 
     In this embodiment, the rear part  21 A has as many recess parts  21   a  as the number of electric circuits  51 . 
     The bottom surfaces of the recess parts  21   a  (the surface closest to the front part  11 ) are flat in this embodiment. 
     The parts between the recess parts  21   a  of the rear part  21 A constitute the inner walls of the recess parts  21   a  and function as ribs along the rear surface of the rear part  21 A. The ribs can prevent the casing  110  from bending or twisting when the detecting device  100  receives loads. 
     [3-2. Lids] 
     The lids  22  are configured to fit the opening parts of the recess parts  21   a.    
     When the lids  22  in this embodiment fit the recess parts  21   a,  the electric circuits  51  housed in the recess parts  21   a  are covered, and the outer surfaces of the lids  22  are flush with the outer surface of the rear part  21 . 
     It is preferable that the material and thickness of the lids  22  be the same as the material and thickness of the rear part  21 A so that the lid body  2 A has a uniform degree of rigidity at the lids  22  and at the rear part  21 A. 
     To eliminate difference in rigidity between the lids  22  and the rear part  21 A, the lids  22  may be formed to be thinner than the rear part  21 A from a material the degree of rigidity of which is higher than the degree of rigidity of the rear part  21 A, or may be formed to be thicker than the rear part  21 A from a material the degree of rigidity of which is lower than the degree of rigidity of the rear part  21 A. 
     Carbon fiber reinforced resin or metals, which have high conductivity and high degree of rigidity, can be used to release heat of the electric circuits. Alternatively, resin, which have low degrees of rigidity and transmit radio waves, can be used so that the detecting device  100 A is suited for wireless communication. 
     The lids  22  may have gaskets at the edge portions. The gaskets prevent dusts and liquids from entering into the recess parts  21   a  to protect the electric circuits  51 . 
     The lids  22  in this embodiment are attachable to and removable from the rear part  21 A, so that the electric circuits  51  can be easily accessed in maintenance of the detecting device  100 A. 
     [4. Supporter] 
     The supporter  4 A supports the radiation detector  3  with the supporting surface  41   a.  The opposite surface of the supporter  4 A from the supporting surface  41   a  is in contact with the inner surface of the rear part  21 A of the casing  110 A. 
     The supporter  4 A in this embodiment fills the whole space between the radiation detector  3  and the rear part  21 A in the casing  110 , except a space beyond the radiation detector  3  in a direction along the imaging surface  312   g  and a space near the inner surface of the lateral part  12 . The shape of the surface of the supporter  4 A that is in contact with the rear part  21 A is therefore the same as the shape of the rear part  21 A. 
     The supporter  4 A and the rear part  21 A may be formed integrally, or the supporter  4 A may be fixed to the rear part  21 A. 
     Methods of fixing the supporter  4 A to the rear part  21 A include gluing with a glue, adhesion with an adhesive tape, fitting a projecting part(s) of the supporter  4 A to a recess part(s) of the rear part  21 A, and fitting a projecting part(s) of the rear part  21 A to s recess part(s) of the supporter  4 A. 
     [5. Electronic Component] 
     The electric circuits  51  in this embodiment are housed in the recess parts  21   a  of the rear part  21 A. 
     In this embodiment, the electric circuits  51  are fixed to the bottom surfaces of the recess parts  21   a.    
     Methods of fixing the electric circuits  51  to the rear part  21 A in this embodiment include fixing with the attaching member  7 , gluing with a glue, and adhesion with an adhesive tape. 
     The electric circuits  51  are separate from the lids  22  of the casing  110 A to avoid receiving external loads on the casing  110 A. 
     The wires  52  in this embodiment are passed through the slits of the recess parts  21   a.    
     ADVANTAGEOUS EFFECTS 
     The detecting device  100 / 100 A has the sensor panel  31  that has flexibility. The flexible sensor panel  31  is less likely to be damaged when the casing  110 / 100 A receives loads or impacts. 
     The sensor panel  31  is also lighter than a known sensor panel because flexible materials are typically lighter than glass. 
     With the light and damage-resistant sensor panel  31 , the supporter  4 / 4 A that supports the sensor panel  31  does not need a high degree of rigidity as compared with a known supporter. Accordingly, the supporter  4 / 4 A can be made of a less amount of material than the known supporter and may not be made of high-rigidity material (e.g., metals or fiber reinforced resin) like the known supporter. This reduces the weight of the supporter  4 / 4 A. 
     The supporter  4 / 4 A made of foam is further lighter. 
     As a result, the detecting device  100 / 100 A is light and can hold the substrate resistant against damages when being pressed or hit. 
     The sensor panel  31  (flexible material) has low heat conductivity. When the sensor panel  31  receives a large amount of heat from the electric circuits  51 , the sensor panel  31  may not diffuse the heat and may have locally hot spots. The sensor panel  31  having partly different temperatures may generate an uneven radiographic image. 
     The detecting device  100 / 100 A, on the other hand, includes the supporter  4  (first supporter  41 ) between the electric circuits  51  and the sensor panel  31 . The supporter  4 / 4 A is made of foam, which typically has high heat-insulating properties. The supporter  4  placed between the electric circuits  51  and the sensor panel  31  can therefore prevent the heat generated by the electric circuits  51  from being transmitted to the sensor panel  31 . 
     The supporter  4 / 4 A also has gaps (recess parts  4   c ), and the heat generated by the electric circuits  51  escapes into the gaps. Accordingly, the supporter  4  can further prevent the heat from being transmitted to the sensor panel  31 . 
     The sensor panel  31  (flexible material) may easily change its shape. When part of the sensor panel  31  changes its shape and comes closer to the electric circuits  51 , the sensor panel  31  may be affected by noises generated by the electric circuits  51 . 
     The detecting device  100 / 100 A, on the other hand, supports the sensor panel  31  with the supporter  4 / 4 A made of foam. As the foam is light, the supporter  4  can be made thick without greatly increasing its weight. The thick supporter  4 / 4 A can keep the distance between the sensor panel  31  and the electric circuits  51  even when the sensor panel  31  changes its shape. The supporter  4 / 4 A thus can prevent the sensor panel  31  from being affected by the noises of the electric circuits  51 . 
     The sensor panel  31  (flexible material) is susceptible to low-frequency vibration. When the vibration arrives at the sensor panel  31 , the sensor panel  31  may increase the amplitude and may be more likely to generate noises. 
     The detecting device  100 / 100 A, on the other hand, supports the sensor panel  31  with the supporter  4 / 4 A made of foam. The foam absorbs low-frequency vibration. The supporter  4 / 4 A can therefore prevent the sensor panel  31  from being affected by low-frequency vibration. 
     The effect of restraining vibration is greater as the filing rate of the supporter  4 / 4 A in the casing  110 / 110 A is greater. 
     Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.