Patent Document

RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Korean Application Number 10-2008-0002070, filed Jan. 8, 2008, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to an X-ray device and, more particularly, to an X-ray device smaller in size and weight than conventional ones, in which device an X-ray irradiation region is visually indicated by laser light without having to use a lamp otherwise provided between an X-ray tube that irradiates a beam of X-rays on an object and a shutter that regulates the irradiation area of the beam of X-rays irradiated on the object. 
     BACKGROUND OF THE INVENTION 
     An X-ray device refers to, e.g., a device that diagnoses the health condition of a human patient or an animal by transmitting a beam of X-rays through an object such as the human patient or the animal and acquiring an X-ray image from the beam of X-rays coming out of the object. 
     Shown in  FIG. 1  is a conventional portable X-ray device. Referring to d 1 , an X-ray device  10  is designed to generate a beam of X-rays and irradiate it on an image capturing unit  20 . As the image capturing unit  20 , use is made of a digital imaging panel that can capture an X-ray image using an X-ray film or a multiplicity of photo sensors. 
     An object  30  whose X-ray image is to be captured is positioned between the X-ray device  10  and the image capturing unit  20 . The beam of X-rays irradiated from the X-ray device  10  pass through the object  30 . Using the beam of X-rays transmitted through the object  30 , the image capturing unit  20  captures an X-ray image of the object  30 . 
     In order to obtain an accurate X-ray image of the object  30 , there is a need to identify an X-ray irradiation region on the object  30  prior to taking the X-ray image of the object  30 . Since the beam of X-rays is not visually recognizable, it is necessary to use an additional unit that enables a user to visually identify the X-ray irradiation region. The unit that enables a user to visually identify and adjust the X-ray irradiation region is typically referred to as a collimator. The collimator serves to direct the light of a lamp toward the X-ray irradiation region, thereby enabling the user to identify the X-ray irradiation region through the lamp light. 
       FIG. 2  shows an exemplary use of the conventional X-ray device  10  that indicates an X-ray irradiation region with a typical lamp. Referring to  FIG. 2 , a collimator for indicating an X-ray irradiation region with a lamp is provided within the X-ray device  10 . In order to take an X-ray image of an object, the collimator illuminates the light of a lamp on an image capturing unit  20 . The light thus illuminated divides the image capturing unit  20  into an illumination region  35  and a non-illumination region  37 . The illumination region  35  of the image capturing unit  20  is equivalent to an actual X-ray irradiation region. Based on the illumination region  35 , the user can identify the actual X-ray irradiation region and can accurately take an X-ray image of a target portion of an object by positioning the target portion in the illumination region  35 . 
       FIG. 3  schematically depicts the internal construction of the conventional X-ray device in which an X-ray irradiation region is indicated with a typical lamp. Referring to  FIG. 3 , a reflection mirror  15  having a specified inclination relative to an X-ray irradiation axis  12  is arranged between an X-ray tube  11  that generates and irradiates a beam of X-rays on an object and a shutter  17  and  18  that regulates the irradiation area of the beam of X-rays. A lamp  13  is arranged below the reflection mirror  15  so that the light emitted from the lamp  13  can be illuminated on the reflection mirror  15 . Then, the light is reflected by the reflection mirror  15  to move along the X-ray irradiation axis  12 . The illumination area of the light moving along the X-ray irradiation axis  12  is regulated by the shutter  17  and  18 , after which the light is illuminated on an image capturing unit. The illumination area of the light on the image capturing unit is the same as the X-ray irradiation region over which the beam of X-rays are actually irradiated by the x-ray tube  11 . The user can identify the X-ray irradiation region by observing the illumination region of the light illuminated on the image capturing unit. 
     For the purpose of simplicity in description,  FIG. 3  shows only an upper shutter blade  17  for regulating an upper edge of the beam of X-rays irradiated on the object and a lower shutter blade  18  for regulating a lower edge of the beam of X-rays. It should be noted, however, that the X-ray device further includes a left shutter blade for regulating a left edge of the beam of X-rays and a right shutter blade for regulating a right edge of the beam of X-rays. 
     With the conventional X-ray device stated above, the lamp has to be arranged between the X-ray tube and the shutter in order for the user to identify the X-ray irradiation region. This makes it necessary to provide a lamp-receiving space between the X-ray tube and the shutter. It is also necessary to provide a space and a vent hole for dissipating the heat generated from the lamp. For that reason, the conventional X-ray device is doomed to be fabricated with a greater size and an increased weight. Furthermore, the conventional X-ray device has a problem in that a large amount of electric power is consumed in operating the lamp. 
     The size of the shutter required to regulate the irradiation area of the beam of X-rays becomes greater as the shutter is positioned farther away from the focal point of the X-ray tube. Typically, the shutter is made of heavy and X-ray impermeable lead that can effectively regulate the irradiation area of the beam of X-rays irradiated on the object. This means that the size and weight of the X-ray device is increased in proportion to the size of the shutter. In case of the conventional X-ray device mentioned above, the distance between the X-ray tube and the focal point must be greater than a specified value to accommodate the lamp and the reflection mirror. This poses a problem in that the conventional X-ray device is constrained to use a shutter having a greater size and an increased weight. 
     SUMMARY OF THE INVENTION 
     In view of the above-noted and other problems inherent in the prior art, it is an object of the present invention to provide a compact and lightweight X-ray device in which a laser is used in place of a lamp to reduce heat generation and power consumption in the X-ray device while enabling a user to readily identify an X-ray irradiation region. 
     Another object of the present invention is to provide a compact and lightweight X-ray device that eliminates the need to use a lamp and a reflection mirror. 
     In one aspect of the present invention provides, there is provided a collimator for use in an X-ray device, comprising: a shutter arranged around an X-ray irradiation axis for regulating an X-ray irradiation region; a laser pointer generating unit for generating a laser pointer used to indicate the X-ray irradiation region regulated by the shutter; and a reflection mirror arranged on the X-ray irradiation axis in an inclined relationship therewith for reflecting the laser pointer toward the X-ray irradiation region. 
     In another aspect of the present invention provides, there is provided an X-ray device comprising: an X-ray generation unit for generating a beam of X-rays; a collimator for regulating an X-ray irradiation region on which the beam of X-rays is irradiated, the collimator being designed to indicate the X-ray irradiation region with a laser pointer; and a power source for supplying an electric current to the X-ray generation unit and the collimator. 
     In a further aspect of the present invention provides, there is provided an X-ray device for irradiating a beam of X-rays on an object to capture an X-ray image of the object, comprising: an X-ray tube for generating the beam of X-rays and irradiating the beam of X-rays on the object; a shutter arranged around an X-ray irradiation axis for regulating an X-ray irradiation region on which the beam of X-rays is irradiated through the object; and a visual indicator unit arranged on the shutter for movement together with the shutter, the visual indicator unit being designed to visually indicate the X-ray irradiation region. 
     In a still further aspect of the present invention provides, there is provided an X-ray device for irradiating a beam of X-rays on an object to capture an X-ray image of the object, comprising: an X-ray tube for generating the beam of X-rays and irradiating the beam of X-rays on the object; an irradiation region setting unit for presetting the size of an X-ray irradiation region on which the beam of X-rays is irradiated through the object; a shutter arranged around an X-ray irradiation axis for regulating the X-ray irradiation region depending on the size preset by the irradiation region setting unit; and a visual indicator unit arranged on the shutter for visually indicating the X-ray irradiation region. 
     In a yet still further aspect of the present invention provides, there is provided an X-ray device for irradiating a beam of X-rays on an object to capture an X-ray image of the object, comprising: an X-ray tube for generating the beam of X-rays and irradiating the beam of X-rays on the object; an irradiation region setting unit for presetting the size of an X-ray irradiation region on which the beam of X-rays is irradiated through the object; a shutter arranged around an X-ray irradiation axis for regulating the X-ray irradiation region depending on the size preset by the irradiation region setting unit; a visual indicator unit arranged independently of the shutter for visually indicating the X-ray irradiation region, the visual indicator unit being movable in synchronism with movement of the shutter; and a drive unit associated with the irradiation region setting unit for driving the visual indicator unit in synchronism with movement of the shutter. 
     With the X-ray device of the present invention, a laser is used in place of a lamp. This makes it possible to reduce heat generation and power consumption in the X-ray device while enabling a user to readily identify an X-ray irradiation region. 
     With the X-ray device of the present invention, a display unit that enables a user to identify an X-ray irradiation region is arranged in a shutter. Therefore, there is no need to arrange a lamp and a reflection mirror between the X-ray tube and the shutter. This makes it possible to fabricate an X-ray device with a small size and a reduced weight. It is also possible to shorten the distance between the focal point of the X-ray tube and the shutter, which makes it possible reduce the size of the shutter that regulates the irradiation area of the beam of X-rays irradiated on an object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments, given in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a conventional portable X-ray device; 
         FIG. 2  shows an exemplary use of the conventional X-ray device that indicates an X-ray irradiation region with a typical lamp; 
         FIG. 3  schematically depicts the internal construction of the conventional X-ray device in which an X-ray irradiation region is indicated with a typical lamp; 
         FIG. 4  is a functional block diagram showing a portable X-ray device provided with a collimator; 
         FIG. 5  schematically illustrates the internal construction of an X-ray device with a laser pointer collimator in accordance with a first embodiment of the present invention; 
         FIG. 6  schematically illustrates the internal construction of an X-ray device in accordance with a second embodiment of the present invention, in which a laser irradiation unit is arranged on the rear surface (at the outer side) of a shutter; 
         FIG. 7  schematically shows a modified example of the X-ray device in accordance with the second embodiment of the present invention, in which the laser irradiation unit is arranged on the front surface (at the inner side) of the shutter. 
         FIGS. 8 ,  9 A and  9 B are views for specifically explaining the shutter employed in the present invention; 
         FIG. 10  is a view schematically showing the laser irradiation unit; 
         FIGS. 11A and 11B  are views illustrating different examples of a laser identification mark; 
         FIG. 12  schematically shows the internal construction of an X-ray device in accordance with a third embodiment of the present invention, which is provided with a laser irradiation unit; 
         FIGS. 13A and 13B  illustrate different examples of an irradiation region setting unit; 
         FIGS. 14A ,  14 B and  14 C illustrate different examples of a laser identification mark appearing on an image capturing unit; 
         FIG. 15  schematically shows a modified example of the X-ray device in accordance with the third embodiment of the present invention, in which a camera unit is used in place of the laser irradiation unit; 
         FIG. 16  is a functional block diagram showing a visual indicator module employed in the X-ray device shown in  FIG. 15 ; 
         FIG. 17  schematically shows the internal construction of an X-ray device in accordance with a fourth embodiment of the present invention, which is provided with an independently arranged laser irradiation unit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, certain embodimefnts of an X-ray device in accordance with the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 4  is a functional block diagram showing a portable X-ray device provided with a collimator. Referring to  FIG. 4 , a user command for preliminarily identifying an X-ray irradiation region is inputted though a user interface  21  prior to taking an X-ray image of an object. Responsive to the user command thus inputted, a control unit  23  causes a battery  25  to supply an electric current to a collimator  27 . Using the electric current, the collimator  27  generates a laser pointer with a specific pattern and directs the laser pointer toward an image capturing unit  20  (see  FIGS. 6 and 7 ). The laser pointer appearing on the image capturing unit  20  enables the user to identify an X-ray irradiation region prior to taking an image of the object. 
     A target portion of the object is positioned in the X-ray irradiation region identified through the laser pointer. Then, a user command for taking the image of the object is inputted through the user interface  21 . In response to the user command thus inputted, the control unit  23  causes the battery  25  to supply an electric current to an X-ray generation unit  11 . Using the electric current, the X-ray generation unit  11  generates a beam of X-rays and irradiates it toward the image capturing unit  20  so that the image capturing unit  20  can take an X-ray image of the object. 
       FIG. 5  schematically illustrates the internal construction of an X-ray device with a laser pointer collimator in accordance with a first embodiment of the present invention. Referring to  FIG. 5 , the X-ray device includes a laser light generator unit  31  which is supplied with an electric current to generate laser light. Examples of the laser light generator  31  include: a solid-state laser in which the crystals of artificial ruby, glass or YAG (yttrium aluminum garnet) containing chromium ions are used as a laser light generating material; a gas-state laser in which a mixture gas of helium and neon, argon, krypton, carbon dioxide or a mixture gas of helium and nitrogen is used as a laser light generating material; and a semiconductor laser in which laser light is generated by allowing an electric current to flow through a p-n junction diode consisting of p-type and n-type gallium arsenide semiconductors. Preferably, the laser light generator  31  is supplied with an electric current from the battery  25 . 
     The X-ray device includes a patterning lens  32  having a plurality of through-holes formed in a specified pattern. The laser light generated in the laser light generator  31  is transmitted through the through-holes so that the laser light corresponding to the pattern of the through-holes can be irradiated on a reflection mirror  15 . The reflection mirror  15  is positioned on an X-ray irradiation axis  12  in an inclined relationship with respect thereto and serves to reflect the laser light coming from the patterning lens  32  in the same direction as the X-ray irradiation axis  12 . 
     The X-ray device includes a shutter for regulating an X-ray irradiation region. The shutter includes shutter blades  17  and  18  symmetrically arranged above and below the X-ray irradiation axis  12 . Typically, shutter blades for regulating the length of the X-ray irradiation region and shutter blades for regulating the width of the X-ray irradiation region are symmetrically arranged at the upper, lower, left and right sides of the X-ray irradiation axis  12 . For the purpose of convenience in description, however, only the shutter blades  17  and  18  arranged at the upper and lower sides of the X-ray irradiation axis  12  are shown in  FIG. 5 . The X-ray irradiation region is changed by increasing or decreasing the gap size between the shutter blades  17  and  18 . The illumination area of the laser light reflected from the reflection mirror  15  is regulated by the shutter blades  17  and  18 . The illumination area of the laser light is substantially the same as the X-ray irradiation region. 
       FIG. 6  schematically illustrates the internal construction of an X-ray device in accordance with a second embodiment of the present invention. Referring to  FIG. 6 , the beam of X-rays generated in an X-ray tube  11  is irradiated on the image capturing unit  20 . A shutter for regulating the X-ray irradiation region is arranged in front of the X-ray tube  11  along the X-ray irradiation direction. It is preferred that the distance d between the focal point of the X-ray tube  11  and the shutter is as small as possible. 
     The shutter includes an upper shutter blade  110  for regulating the upper edge of the X-ray irradiation region and a lower shutter blade  111  for regulating the lower edge of the X-ray irradiation region. Although only the upper and lower shutter blades  110  and  111  are shown in  FIG. 6  for the purpose of convenience in description, it should be appreciated that the shutter further includes left and right shutter blades for regulating the left and right edges of the X-ray irradiation region. The beam of X-rays emitted from the X-ray tube  11  is irradiated on the image capturing unit  20  through the shutter, at which time the X-ray irradiation region on the image capturing unit  20  are regulated by the upper, lower, left and right shutter blades. 
     Laser irradiation units  120  and  121 , which constitute a visual indicator unit defined in the claims, are attached to the rear surfaces (the outer sides) of the upper shutter blade  110  and the lower shutter blade  111  opposite from the X-ray tube  11 . The laser irradiation unit  120  attached to the upper shutter blade  110  emits laser light along the upper edge of the beam of X-rays irradiated on the image capturing unit  20  through the shutter. The laser irradiation unit  121  attached to the lower shutter blade  111  emits laser light along the lower edge of the beam of X-rays irradiated on the image capturing unit  20  through the shutter. The laser light emitted from the laser irradiation units  120  and  121  indicates the upper and lower edges of the X-ray irradiation region on the image capturing unit  20 . 
     Similarly, laser irradiation units (not shown) are attached to the rear surfaces (the outer sides) of the left shutter blade and the right shutter blade opposite from the X-ray tube  11 . The laser irradiation unit attached to the left shutter blade emits laser light along the upper edge of the beam of X-rays irradiated on the image capturing unit  20  through the shutter. The laser irradiation unit attached to the right shutter blade emits laser light along the right edge of the beam of X-rays irradiated on the image capturing unit  20  through the shutter. The laser light emitted from the laser irradiation units attached to the left and right shutter blades indicates the left and right edges of the X-ray irradiation region on the image capturing unit  20 . 
       FIG. 7  schematically shows a modified example of the X-ray device in accordance with the second embodiment of the present invention. The X-ray device shown in  FIG. 7  is essentially the same as the X-ray device illustrated in  FIG. 6 , except that the laser irradiation units  120  and  121  are attached to the front surfaces (the inner sides) of the upper shutter blade  110  and the lower shutter blade  111  that face toward the X-ray tube  11 . This holds true in case of the laser irradiation units attached to the left shutter blade and the right shutter blade. 
       FIGS. 8 ,  9 A and  9 B are views for specifically explaining the shutter employed in the present invention. Referring to  FIG. 8 , a first shutter includes an upper shutter blade  110  and a lower shutter blade  111 , both of which serve to shift the X-ray irradiation region in the vertical direction. A second shutter includes a left shutter blade  113  and a right shutter blade  114 , both of which serve to shift the X-ray irradiation region in the lateral direction. The first and second shutters are moved vertically and laterally in an overlapped state to form an aperture S of varying size that defines the X-ray irradiation region. 
     The movement of the first and second shutters will be described in detail with reference to  FIGS. 9A and 9B . Referring first to  FIG. 9A  which is a side view of the shutters, the upper shutter blade  110  and the lower shutter blade  111  of the first shutter are curved to have a first radius r 1  from the focal point of the beam of X-rays. The upper shutter blade  110  and the lower shutter blade  111  are movable upwards or downwards along the arc of a circle with the first radius r 1 . The laser irradiation units  120  and  121  are attached to the lower end of the upper shutter blade  110  and the upper end of the lower shutter blade  111 , respectively. As the upper shutter blade  110  and the lower shutter blade  111  move upwards or downwards along the arc, the laser irradiation units  120  and  121  are also moved along the same trajectory as that of the upper shutter blade  110  and the lower shutter blade  111 . The laser irradiation unit  120  attached to the upper shutter blade  110  emits laser light in the direction A along the upper edge of the beam of X-rays to indicate the upper edge of the X-ray irradiation region on the image capturing unit  20 . The laser irradiation unit  121  attached to the upper shutter blade  111  emits laser light in the direction B along the lower edge of the beam of X-rays to indicate the lower edge of the X-ray irradiation region on the image capturing unit  20 . 
     Referring next to  FIG. 9B  which is a top plan view of the shutters, the left shutter blade  113  and the right shutter blade  114  of the second shutter are curved to have a second radius r 2  from the focal point of the beam of X-rays. The left shutter blade  113  and the right shutter blade  114  are movable to the left or the right along the arc of a circle with the second radius r 2 . Laser irradiation units  123  and  124  are attached to the right end of the left shutter blade  113  and the left end of the right shutter blade  114 , respectively. As the left shutter blade  113  and the right shutter blade  114  move to the left or the right along the arc, the laser irradiation units  123  and  124  are also moved along the same trajectory as that of the left shutter blade  113  and the right shutter blade  114 . The laser irradiation unit  123  attached to the left shutter blade  113  emits laser light in the direction C along the left edge of the beam of X-rays to indicate the left edge of the X-ray irradiation region on the image capturing unit  20 . The laser irradiation unit  124  attached to the right shutter blade  114  emits laser light in the direction D along the right edge of the beam of X-rays to indicate the right edge of the X-ray irradiation region on the image capturing unit  20 . 
       FIG. 10  schematically shows the construction of the laser irradiation unit. Referring to  FIG. 10 , the laser irradiation unit includes a laser light generator  151  for generating laser light and a patterning lens  153  for changing the laser light into a specified pattern before it is irradiated on the image capturing unit. The laser light generator  151  may be a solid-state laser, a gas-state laser or a semiconductor laser, the classification of which depends on the material used and the mode of operation. The patterning lens  153  has a plurality of through-holes arranged in a predetermined pattern and designed to create a laser identification mark that indicates the upper, lower, left or right edges of the X-ray irradiation region. The laser light generated in the laser light generator  151  is split into an array of light beams of a predetermined pattern while passing through the through-holes of the patterning lens  153 . Then the array of light beams is irradiated on the image capturing unit and is used as the laser identification mark that indicates the X-ray irradiation region.  FIGS. 11A and 11B  illustrate different examples of the laser identification mark formed on the image capturing unit  20  by the array of light beams passing through the through-holes of the patterning lens  153 . 
     While the laser light is employed to indicate the X-ray irradiation region in the foregoing embodiments, it may also be possible to use other coherent light depending on the application of the present invention. This also falls within the scope of the present invention. 
       FIG. 12  schematically shows the internal construction of an X-ray device in accordance with a third embodiment of the present invention. Referring to  FIG. 12 , the beam of X-rays generated in the X-ray tube  11  is irradiated on the image capturing unit  20 . A shutter for regulating the X-ray irradiation region is arranged in front of the X-ray tube  11  along the X-ray irradiation direction. It is preferred that the distance d between the focal point of the X-ray tube  11  and the shutter is as small as possible. 
     The shutter includes an upper shutter blade  210  for regulating the upper edge of the X-ray irradiation region and a lower shutter blade  211  for regulating the lower edge of the X-ray irradiation region. Although only the upper and lower shutter blades  210  and  211  are shown in  FIG. 12  for the purpose of convenience in description, it should be appreciated that the shutter further includes left and right shutter blades for regulating the left and right edges of the X-ray irradiation region. 
     The upper and lower shutter blades  210  and  211  and the left and right shutter blades are moved vertically and laterally depending on the size of the X-ray irradiation region preset by an irradiation region setting unit  230 . The irradiation region setting unit  230  includes a setting part for presetting the size of the X-ray irradiation region and a drive part for driving the shutter depending on the size of the X-ray irradiation region preset by the setting part. Although not shown in the drawings, the drive part includes a plurality of gears operatively connected to the shutter and an electric motor for rotating the gears. 
     Depending on the size of the X-ray irradiation region preset by the setting part, the drive part displaces the upper and lower shutter blades  210  and  211  and the left and right shutter blades to form an aperture corresponding to the X-ray irradiation region on the image capturing unit  20 . 
       FIGS. 13A and 13B  illustrate different examples of the setting part of the irradiation region setting unit  230 . In one example of the setting part illustrated in  FIG. 13A , a rotary knob is mounted to a housing of the X-ray device. A reference mark that indicates the current size of the X-ray irradiation region is placed on the top surface of the rotary knob. A plurality of graduations “1”, “2” and “3” that indicates the varying size of the X-ray irradiation region is placed on the housing  61  of the X-ray device. The size of the X-ray irradiation region can be arbitrarily set by turning the rotary knob so that the reference mark on the rotary knob can be aligned with one of the graduations “1”, “2” and “3.” 
     In another example of the setting part illustrated in  FIG. 13B , the setting part includes a display and a keypad arranged on the surface of the housing of the X-ray device. The key pad includes a plurality of size selection keys “1”, “2” and “3” that can be pressed to select the size of the X-ray irradiation region and an input key that can be pressed to input the size of the X-ray irradiation region selected. If a user presses, e.g., the size selection key “2”, the length and width of the X-ray irradiation region is displayed on the display to read, e.g., “SIZE 2, 45 cm×45 cm”. Then the user presses the input key to finalize the task of selecting the size of the X-ray irradiation region. 
     Referring again to  FIG. 12 , a laser irradiation unit  220  is arranged on the opposite side of the upper shutter blade  210  from the X-ray tube  11 . The laser irradiation unit  220  irradiates laser light toward the image capturing unit  20  to indicate the X-ray irradiation region whose size has been selected by the irradiation region setting unit  230 . 
       FIGS. 14A ,  14 B and  14 C illustrate different examples of the laser identification mark appearing on the image capturing unit. Referring to  FIGS. 14A and 14B , the size of the X-ray irradiation region preset through the use of the irradiation region setting unit  230  is indicated on the image capturing unit  20  by irradiating the laser light to form a laser identification mark having an angle bracket shape or a square shape. Turning to  FIG. 14C , the size of the X-ray irradiation region preset through the use of the irradiation region setting unit  230  is indicated on the image capturing unit  20  by irradiating the laser light to form a laser identification mark having a dot axis shape. 
     Referring again to  FIG. 12 , it is preferred that the laser irradiation unit  220  is arranged in a position nearest to the shutter insofar as it does not interrupt the beam of X-rays irradiated toward the image capturing unit  20  through the shutter. The laser irradiation unit  220  is fixedly arranged on the opposite surface of the shutter from the X-ray tube  11  so that the deviation between the actual X-ray irradiation region actually irradiated by the beam of X-rays and the target X-ray irradiation region indicated by the laser identification mark is equal to or smaller than a first threshold value. 
     If the user presets the X-ray irradiation region through the use of the irradiation region setting unit  230 , the shutter blades are moved to ensure that the beam of X-rays is irradiated on the preset X-ray irradiation region. The user can determine the actual X-ray irradiation region by observing the laser identification mark mapped to the size of the preset X-ray irradiation region. 
       FIG. 15  schematically shows a modified example of the X-ray device in accordance with the third embodiment of the present invention, in which a camera unit  321  is used in place of the laser irradiation unit  220 . Referring to  FIG. 15 , the beam of X-rays generated in the X-ray tube  11  is irradiated toward the image capturing unit  20 . A shutter for regulating the X-ray irradiation region is arranged in front of the X-ray tube  11  along the X-ray irradiation direction. It is preferred that the distance d between the focal point of the X-ray tube  11  and the shutter is as small as possible. 
     The shutter includes an upper shutter blade  310  for regulating the upper edge of the X-ray irradiation region and a lower shutter blade  311  for regulating the lower edge of the X-ray irradiation region. Although only the upper and lower shutter blades  310  and  311  are shown in  FIG. 15  for the purpose of convenience in description, it should be appreciated that the shutter further includes left and right shutter blades for regulating the left and right edges of the X-ray irradiation region. 
     The upper and lower shutter blades  310  and  311  and the left and right shutter blades are moved vertically and laterally depending on the size of the X-ray irradiation region preset by an irradiation region setting unit  330 . The irradiation region setting unit  330  includes a setting part for presetting the size of the X-ray irradiation region and a drive part for driving the shutter depending on the size of the X-ray irradiation region preset by the setting part. Although not shown in the drawings, the drive part includes a plurality of gears operatively connected to the shutter and an electric motor for rotating the gears. 
     Depending on the size of the X-ray irradiation region preset by the setting part, the drive part displaces the upper and lower shutter blades  210  and  211  and the left and right shutter blades to form an aperture corresponding to the X-ray irradiation region on the image capturing unit  20 . 
     A camera unit  321  is arranged on the opposite surface of the shutter from the X-ray tube  11 . The camera unit  321  is designed to take an image of the X-ray irradiation region on the image capturing unit  20 . 
     It is preferred that the camera unit  321  is arranged in a position nearest to the shutter insofar as it does not interrupt the beam of X-rays irradiated toward the image capturing unit  20  through the shutter. The camera unit  321  is fixedly arranged on the opposite surface of the shutter from the X-ray tube  11  so that the deviation between the actual X-ray irradiation region actually irradiated by the beam of X-rays and the target X-ray irradiation region taken by the camera unit  321  is equal to or smaller than a first threshold value. 
       FIG. 16  is a functional block diagram showing a visual indicator module employed in the X-ray device shown in  FIG. 15 . Referring to  FIG. 16 , the visual indicator that forms a part of the X-ray device includes a camera unit  321  for taking an image of the X-ray irradiation region, a display unit  325  for displaying an actual X-ray irradiation region and a control unit  323  responsive to a user command inputted through a setting unit for controlling the display unit  325  to display the actual X-ray irradiation region extracted from the image of the X-ray irradiation region. 
     The control unit  323  is supplied with the image of the X-ray irradiation region taken by the camera unit  321 . Responsive to the user command inputted through the setting unit, the control unit  323  identifies the actual X-ray irradiation region contained in the image of the X-ray irradiation region. Then the control unit  323  controls the display unit  325  to display the actual X-ray irradiation region with or without an identification mark. 
       FIG. 17  schematically shows the internal construction of an X-ray device in accordance with a fourth embodiment of the present invention, which is provided with an independently arranged laser irradiation unit. As shown in  FIG. 17 , the X-ray device includes laser irradiation units  420  and  421  arranged independently of the shutter. The X-ray device further includes an irradiation region setting unit  430  that displaces the upper and lower shutter blades  410  and  411  and the left and right shutter blades to form an aperture corresponding to the X-ray irradiation region preset by the user. The X-ray device further includes a laser drive unit  240  associated with the irradiation region setting unit  430 . The laser drive unit  240  controls the laser irradiation units  420  and  421  in synchronism with the movement of the shutter. In other words, the laser irradiation units  420  and  421  are controlled by the laser drive unit  240  to irradiate a beam of X-rays toward the image capturing unit  20  so that a laser identification mark indicating the X-ray irradiation region preset through the use of the irradiation region setting unit  430  can be displayed on the image capturing unit  20 . 
     The X-ray device of the foregoing embodiments may be operated through the use of a general computer having a computer-readable medium that stores a program needed to operate the X-ray device. Examples of the computer-readable medium include a magnetic storage medium (e.g., a ROM, a floppy disk and a hard disk), an optical recording medium (e.g., a CD ROM and a DVD) and a carrier wave (e.g., transmission through the Internet). 
     While certain preferred embodiments of the present invention have been described hereinabove, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention defined in the claims.

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