Abstract:
A radiographic imaging apparatus includes a radiographic-image detecting unit configured to detect radiation and convert the detected radiation to an image signal; a wireless transmission unit configured to wirelessly transmit the image signal to an external device; and a housing configured to cover the radiographic-image detecting unit and the wireless transmission unit, wherein a first side surface of the housing has a first opening for wireless transmission performed by the wireless transmission unit, and a second side surface of the housing adjoining the first side surface has a second opening for wireless transmission by the wireless transmission unit.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a radiographic imaging apparatus that detects radiation and acquires a radiographic image. 
       BACKGROUND ART 
       [0002]    Radiographic imaging apparatuses using flat panel sensors formed of thin-film semi-conductor material on insulating substrates are being put to practical use as imaging apparatuses for medical image diagnosis and nondestructive testing by radiation. A radiographic imaging apparatuses using a flat panel sensor converts radiation that has been transmitted through a subject to be tested to an analog electrical signal at the flat panel sensor and acquires a digital image signal by carrying out analog-to-digital conversion. In medical image diagnosis, a digital radiographic imaging apparatus is used for picking up still images and moving images, such as fluoroscopic images. 
         [0003]    Today, many digital radiographic imaging apparatuses are commercially produced as portable radiographic imaging apparatuses that are thin and lightweight. As a digital radiographic imaging apparatus according to the related art, a wireless radiographic imaging apparatus that wirelessly transmits and receives data to and from an external device to improve portability is disclosed in PTL 1. 
         [0004]    In general, the housing of a digital radiographic imaging apparatus is a metal housing or a molded housing covered with an electromagnetic shield. In this way, the stiffness of the radiographic imaging apparatus is maintained, and the electronic circuits inside the radiographic imaging apparatus are protected from external electromagnetic noise. A decrease in image quality of the radiographic images will have an adverse effect on healthcare. Therefore, such a decrease in image quality of the radiographic images due to electromagnetic noise must be prevented. 
         [0005]    Unfortunately, when a wireless communication unit, such as an antenna, is disposed inside the housing, it is difficult to perform satisfactory wireless communication because the housing blocks external electromagnetic waves. Therefore, an opening is formed in the housing near the wireless communication unit to ensure satisfactory wireless communication. A large opening will ensure satisfactory wireless communication. However, the large opening will cause a reduction in the stiffness of the radiographic imaging apparatus. 
       CITATION LIST 
     Patent Literature 
       [0006]    PTL 1: Japanese Patent No. 03990914 
       SUMMARY OF INVENTION 
       [0007]    The present invention has been made in consideration of the above situations and provides a radiographic imaging apparatus that ensures optimal wireless communication while maintaining the stiffness of the radiographic imaging apparatus. 
         [0008]    The present invention provides a radiographic imaging apparatus including a radiographic-image detecting unit configured to detect radiation and convert the detected radiation to an image signal; a wireless transmission unit configured to wirelessly transmit the image signal to an external device; and a housing configured to cover the radiographic-image detecting unit and the wireless transmission unit, wherein a first side surface of the housing has a first opening for wireless transmission performed by the wireless transmission unit, and a second side surface of the housing adjoining the first side surface has a second opening for wireless transmission by the wireless transmission unit. 
         [0009]    Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
           [0011]      FIG. 1  is a sectional side view of an electronic cassette according to a first embodiment. 
           [0012]      FIG. 2A  illustrates a schematic arrangement of antenna covers according to the first embodiment. 
           [0013]      FIG. 2B  illustrates a schematic arrangement of antenna covers according to the first embodiment. 
           [0014]      FIG. 2C  illustrates a schematic arrangement of antenna covers according to the first embodiment. 
           [0015]      FIG. 2D  illustrates a schematic arrangement of antenna covers according to the first embodiment. 
           [0016]      FIG. 2E  illustrates a schematic arrangement of antenna covers according to the first embodiment. 
           [0017]      FIG. 3  is a sectional top view of an electronic cassette according to a second embodiment. 
           [0018]      FIG. 4  is a sectional side view of the electronic cassette according to the second embodiment. 
           [0019]      FIG. 5  is a sectional top view of an electronic cassette according to a third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    Preferred embodiments of the present invention will be described in detail in accordance with the accompanying drawings. 
       First Embodiment 
       [0021]      FIGS. 1 and 2A  to  2 E illustrate the configuration of a radiographic imaging apparatus according to this embodiment. The radiographic imaging apparatus according to this embodiment will be described with reference to  FIGS. 1 and 2A  to  2 E. 
         [0022]      FIG. 1  is a sectional side view of an electronic cassette according to this embodiment. As illustrated in  FIG. 1 , the electronic cassette according to this embodiment is shaped as a cuboid. 
         [0023]    A housing  101  of an electronic cassette  10  includes a stiff metal housing part  101   b  and a radiation incident surface formed of a high radiation-transmittance material  101   a.    
         [0024]    The housing  101  accommodates a radiographic image sensor  102  that functions as a radiographic image detecting unit detecting radiation and converting the detected radiation to an image signal. A sensor retaining plate  107  is attached to the radiographic image sensor  102  on the surface opposite to the radiation incident surface of the radiographic image sensor  102 . The sensor retaining plate  107  and the radiographic image sensor  102  are joined together with a radiation shielding plate  108  interposed therebetween so as to protect electric substrates, including a control circuit portion  104 , and prevent image degradation due to backscattering. 
         [0025]    In the radiographic image sensor  102 , a plurality of pixels, each having a converter element converting the radiation to a charge corresponding to the radiation and a switching element transferring an electrical signal based on the charge, are arranged two-dimensionally. The radiographic image sensor  102  is connected to a readout circuit portion  106  that reads out electrical signals from the pixels via a flexible circuit board  105 . 
         [0026]    The readout circuit portion  106  and the control circuit portion  104  that controls electrical signals are connected via a cable (not shown). 
         [0027]    A wireless transmission and reception antenna  103  functions as a wireless receiving unit and a wireless transmitting unit transmitting image signals to and from external devices. Instead of the wireless transmission and reception antenna  103 , a wireless transmission antenna mainly for transmitting image signals may be used. 
         [0028]    The wireless transmission and reception antenna  103  is connected to the control circuit portion  104  via a cable (not shown). 
         [0029]    Since a metal housing is used in this embodiment as described above, when the antenna radiating property is taken into consideration, it is desirable that the wireless transmission and reception antenna  103  be a protrusion on the housing  101  that is covered with a non-conductive cover. 
         [0030]    However, with such a configuration, it is difficult to maintain the stiffness of the electronic cassette  10  having an external size substantially the same as a film cassette. Thus, in this embodiment, the wireless transmission and reception antenna  103  is disposed on the side opposite to the side on which the radiation incident surface of the radiographic image sensor  102  is disposed. In this way, size of the electronic cassette  10  becomes substantially the same as that of a film cassette. 
         [0031]    Additionally, for an optimal antenna radiating property, antenna covers  11  and  12  (first non-conductive member and second non-conductive member) including non-conductive members are disposed on adjoining surfaces of the housing  101  near the wireless transmission and reception antenna  103 . The antenna covers  11  and  12  of the housing  101  are installed in openings, each having a length larger than one half of wavelength  1  of the antenna frequency F. 
         [0032]    For example, when the wireless transmission and reception antenna  103  is a multiband antenna, openings each having a length larger than one half of the longest wavelength should be formed. 
         [0033]    As described above, optimal wireless transmission is achieved by forming a first opening in a first side surface of the housing  101  and forming a second opening in a second side surface adjoining the first side surface. 
         [0034]    In this embodiment, the stiffness of the housing  101  is maintained by forming the antenna openings such that an edge section  101   c  shared by two surfaces of the housing  101  is left. 
         [0035]    With such a configuration, the radiating property of the antenna and the stiffness of the housing  101  are ensured, and the size of the device (the size compatible with the size of the cassette). 
         [0036]    The antenna covers  11  and  12  are light-shielding members and prevent the radiographic image sensor  102  from being exposed to external light. 
         [0037]      FIGS. 2A to 2E  illustrate example arrangements of the antenna covers of this embodiment. 
         [0038]    In  FIG. 2A , the antenna covers  11  and  12  are disposed on a side surface of the electronic cassette  10  and the surface opposing the radiation incident surface. The antenna covers  11  and  12  are provided as an integrated structure such that the antenna covers  11  and  12  can be removed from the electronic cassette  10  together with the edge section  101  as one piece. By provided the antenna covers as an integrated structure, the number of components can be reduced. 
         [0039]    In  FIG. 2B , antenna covers  11  and  12  are disposed separately on a side surface of the electronic cassette  10  and the surface opposing the radiation incident surface. Compared with the arrangement in  FIG. 2A , stiffness is increased, and the size can be decreased (especially, the thickness of the housing and frame can be reduced). 
         [0040]    In  FIG. 2C , antenna covers  12  and  13  are disposed separately on two adjoining side surfaces near a corner of the electronic cassette  10 . Compared with the arrangement in  FIG. 2B , the stiffness of the corner sections is lowered but an optimal antenna radiating property can be acquired when, for example, a metal structure is installed behind the electronic cassette  10 . 
         [0041]    In  FIG. 2D , antenna covers  12 ,  13 , and  14  are disposed separately on two adjoining side surfaces and on the surface opposing the radiation incident surface near a corner of the electronic cassette  10 . Compared with the other example arrangements, the stiffness is lowered and the size is large (in particular, the frame is thick) but the antenna radiating property is optimal, providing a structure effective in environments with unsatisfactory wireless communication conditions. 
         [0042]    In  FIG. 2E , antenna covers  11  and  12  are disposed on a side surface of the electronic cassette  10  and the surface opposing the radiation incident surface. In addition, an antenna cover  13  is disposed on another side surface on which the antenna cover  12  is not disposed, and an antenna  14  is provided on the surface opposing the radiation incident surface. Compared with the other example arrangements, the antenna property is improved even more by providing two antennas, each of which has the same structure as the antenna illustrated in  FIG. 2B . Any of the arrangements in  FIGS. 2A ,  2 B, and  2 C can be combined; for example, the arrangements in  FIGS. 2B and 2C  may be combined. 
         [0043]    Although the width of the edge sections of the housing differ depending on the arrangement, when there is no restrictions on the external size of the housing, the width of the edge sections are set to a value that ensures resistance against impacts, such as drops. 
         [0044]    Separate antenna covers, such as those illustrated in  FIG. 2B , are also provided in the arrangements illustrated in  FIGS. 2C ,  2 D, and  2 E. The antenna cover parts may instead be integrated such as those illustrated in  FIG. 2A . 
       Second Embodiment 
       [0045]      FIGS. 3 and 4  illustrate the internal structure of a radiographic imaging apparatus according to this embodiment. The radiographic imaging apparatus according to this embodiment will be described with reference to  FIGS. 3 and 4 . 
         [0046]      FIG. 3  is a sectional top view from the back side of the radiation incident surface of an electronic cassette  200  according to this embodiment.  FIG. 4  is a sectional side view of the electronic cassette  200  according to this embodiment. 
         [0047]    The housing of the electronic cassette  200  accompanies a radiographic image sensor  201  and a sensor retaining plate  211 , which are joined together with a radiation-shielding and noise-shielding metal shielding plate  210  interposed therebetween. In the radiographic image sensor  201 , a plurality of pixels, each having a converter element converting radiation to a charge corresponding to the radiation and a switching element transferring an electrical signal based on the charge, are arranged two-dimensionally. A driving circuit portion  203  outputs a driving signal having a voltage that makes the switching element conductive to the switching element via a flexible circuit board. The driving circuit portion  203  and a readout circuit portion  202  that reads out electrical signals from the pixels are respectively connected to a first side and a second side different from the first side of the radiographic image sensor  201 . The readout circuit portion  202  is covered with a metal shield portion  206  that prevents a reduction in image quality due to noise. The readout circuit portion  202  and a control circuit portion  204  that controls the electrical signal are connected via a cable (not shown). 
         [0048]    A wireless communication unit  205  is disposed near a side opposing the readout circuit portion  202  so that the radiating property is not degraded and/or the resonant frequency is not changed due to the influence of surrounding conductive members. The periphery is covered with a non-conductive material (not shown). The influence of noise can be reduced by disposing the wireless communication unit  205  on the surface opposite to the radiation incident surface of the radiographic image sensor  201  with the radiation-shielding and noise shielding metal shielding plate  210 . 
         [0049]    The radiographic imaging apparatus according to this embodiment also includes a power source  208  supplying power to the radiographic image sensor  201  and the circuit boards. The power source  208 , together with the wireless communication unit  205 , enables wireless communication. 
         [0050]    To reduce the size of the electronic cassette, all components are disposed on the surface opposing the radiation incident surface of the radiographic image sensor  201 . For example, with an apparatus that does not require a size reduction may have the components disposed on a surface not opposing the radiation incident surface of the radiographic image sensor  201 . 
       Third Embodiment 
       [0051]    According to the third embodiment, an electronic cassette accommodates a double-scanning radiation sensor having two readout circuit portions, which enable high-speed readout and are disposed at two opposing sides. In such a case, a wireless communication unit cannot be disposed at a side opposing the readout circuit portion. By taking into consideration such a point, the electronic cassette having a double-scanning radiation sensor according to this embodiment will be described with reference to  FIG. 5 . 
         [0052]      FIG. 5  is a sectional top view from the back side of the radiation incident surface of the electronic cassette according to this embodiment. Readout circuit portions  202   a  and  202   b  that readout electrical signals from pixels are connected to opposing sides of a radiographic image sensor  201 . A driving circuit portion  203  is connected to a third side. By disposing a wireless communication unit  205  at the center C of the remaining side (fourth side) to which neither the readout circuit portions  202   a  and  202   b  nor the driving circuit portion  203  is connected, the influence of noise and the external size can be reduced. 
         [0053]    While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
         [0054]    This application claims the benefit of Japanese Patent Application No. 2009-270096, filed Nov. 27, 2009, which is hereby incorporated by reference herein in its entirety.