Abstract:
The present invention relates to an X-ray imaging device including a plurality of X-ray sources. The X-ray image photographing device, according to the present invention, is an X-ray imaging device comprising an X-ray generation unit and a detector having an object being inspected placed therebetween and are arranged to face each other, wherein the X-ray generation unit includes the plurality of X-ray sources which are arranged along at least two rows located at different distances from the object being inspected and respectively irradiate X-rays toward the object being inspected.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to an X-ray image obtaining apparatus including a plurality of X-ray sources. 
         [0003]    2. Related Art 
         [0004]    Recently, an X-ray imaging technology is grafted on a semiconductor section, and thus is rapidly developed into a digital X-ray imaging technology having various advantages, such as relatively high resolution, a wide dynamic range, and the easy generation of an electrical signal, and the simple processing and storage of data instead of a conventional analog method using a film. The digital-based imaging technology strongly reflects a clinical and environmental need called an early diagnosis of a disease based on the excellent diagnosability of a digital image. 
         [0005]    Accordingly, there has been introduced “digital mammography”, that is, a breast-dedicated X-ray photographing technology capable of detecting a breast cancer and a lesion and fine calcification for an early diagnosis by representing the internal structure of the breast, that is, a specimen, in a high-resolution image using the biological tissue contrast ability unique to X-rays. Such digital mammography is rapidly spread due to unique characteristics, such as the magnification of an image, a reduction of a photographing number, an increase of resolution, and the minimization of atomic bombing through control of brightness and contrast ratio, in addition to various advantages of the digital X-ray imaging technology. 
         [0006]    Furthermore, in a digital image obtaining apparatus for obtaining a two-dimensional projection image, a diagnosis is not easy if an abnormal portion (lesion) of a specimen is covered by a human tissue, etc. As a solution for such a problem, after images of the specimen are obtained at various angles, a three-dimensional tomosynthesis image of the specimen may be generated by reconfiguring the obtained images. To this end, a computed tomography (CT) or digital breast tomosynthesis (DBT) apparatus, that is, an example of an existing X-ray imaging apparatus, generates multi-directional X-ray projection images by radiating X-rays to a specimen while relatively rotating a single X-ray source around the specimen and generates a three-dimensional image by reconfiguring the multi-directional X-ray projection images. 
         [0007]    A conventional DBT apparatus is described with reference to  FIG. 1 . The conventional DBT apparatus  1  a support row  11  of a vertical pillar shape which has a lower end fixed to the bottom, a device body  10  which is installed to move up and down along the support row  11 , a detector  30  which is installed on the bottom of the device body  10 , and an X-ray generation unit  20  which is rotated around a specimen BR through a rotary support unit  22  rotatably connected to the device body  10 . 
         [0008]    In such a DBT apparatus  1 , when a testee enters a photographing location, the device body  10  moves up and down along the support row  11 , and thus the height of the device body  10  is adjusted so that the specimen (e.g., the breast) of the testee is placed on the detector  30 . Next, the X-ray generation unit  20  photographs the specimen BR while rotating and moving from the location of the X-ray generation unit  20  indicated by a dotted line on the left side to the location of the X-ray generation unit  20  indicated by a dotted line on the right side by rotating the rotary support unit  22 . 
         [0009]    In this case, in general, the X-ray photographing is performed in accordance with a continuous-shoot method for photographing the specimen BR when the X-ray generation unit  20  reaches a specific angular interval while rotating around the specimen BR. However, such a continuous-shot method has a problem in that image quality is deteriorated because X-ray photographing is performed while the X-ray generation unit  20  rotates and moves and thus a motion blur phenomenon in which the boundary of an image focused on the detector  30  unclearly appears is generated. 
         [0010]    In order to prevent such a motion blur phenomenon, there is used a stop-and-shot method for photographing the specimen BR after the X-ray generation unit  20  is fully stopped at each angular interval in which photographing is to be performed. However, such a stop-and-shot method has problems in that the photographing time is generally lengthened and vibration and noise are generated because X-ray photographing has to be performed in the state in which the X-ray generation unit  20  has been fully stopped at each specific angular interval and then the X-ray generation unit  20  has to move. 
       SUMMARY 
       [0011]    The present invention has been made to solve the above conventional problems, and an object of the present invention is to provide an X-ray image obtaining apparatus capable of obtaining a high-resolution three-dimensional tomosynthesis image. 
         [0012]    An X-ray image obtaining apparatus of the present invention for achieving the above object is an X-ray image obtaining apparatus including an X-ray generation unit and a detector disposed to face each other with a specimen therebetween, wherein the X-ray generation unit includes a plurality of X-ray sources which is disposed in at least two rows at different distances from the specimen and radiates X-rays toward the specimen. 
         [0013]    The at least two rows may be arc forms having different radii. 
         [0014]    The plurality of X-ray sources disposed in the at least two rows may be crisscross disposed at different angles with respect to the specimen so that the X-rays toward the specimen do not overlap. 
         [0015]    The at least two rows may be disposed back and forth and may be arc shapes having the same radius. 
         [0016]    The X-ray generation unit may include moving means for adjusting the interval between the at least two rows. 
         [0017]    The plurality of X-ray sources may sequentially operate for each row or sequentially operate while changing the rows. 
         [0018]    Each of the plurality of X-ray sources may be an electric field emission type X-ray source using a nanostructure material electric field emission type emitter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a front view of a conventional DBT apparatus. 
           [0020]      FIG. 2  is a front view of an X-ray image obtaining apparatus according to the present invention. 
           [0021]      FIG. 3  is a front view of an X-ray generation unit shown in  FIG. 2 . 
           [0022]      FIG. 4( a )  is a front view of the X-ray generation unit shown in  FIG. 2 , and  FIG. 4( b )  is a plan view of the X-ray generation unit. 
           [0023]      FIG. 5( a )  is a front view of the X-ray generation unit shown in  FIG. 2 , and  FIG. 5( b )  is a plan view of the X-ray generation unit. 
           [0024]      FIG. 6( a )  is a front view of the X-ray generation unit shown in  FIG. 2 , and  FIG. 6( b )  is a plan view of the X-ray generation unit. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Hereinafter, preferred embodiments of the present invention are described in detail with reference to the accompanying drawings. 
         [0026]      FIG. 2  is a front view of an X-ray imaging apparatus according to the present invention. Referring to  FIG. 2 , the X-ray image obtaining apparatus  100  according to the present invention includes a support row  111  of a vertical pillar shape and a device body  110  installed in such a way as to move up and down along the support row  111 . A generator or X-ray generation unit  120  for radiating X-ray toward a specimen BR is installed on the upper side of the device body  110 . A detector  130  which faces the X-ray generation unit  120  and receives the X-rays radiated by the X-ray generation unit  120  is installed on the bottom of the device body  110 . 
       First Embodiment 
       [0027]      FIG. 3  is a front view of the X-ray generation unit shown in  FIG. 2 . In accordance with the first embodiment of the present invention shown in  FIG. 3 , when viewed from the front of the X-ray generation unit  120 , that is, in a testee direction, the X-ray generation unit  120  includes a plurality of X-ray sources  123  and  124  which has different distances from the specimen and is arranged to form at least two rows and a mounting unit  122  for detachably installing the plurality of X-ray sources  123  and  124  on the X-ray generation unit  120 . 
         [0028]    In this case, it is preferred that each of the rows of the X-ray sources  123  and  124  forms an arc shape for the specimen BR, but is not limited thereto. Each of the rows may form a straight-line shape. Furthermore, each of the X-ray sources  123  and  124  may be configured to include X-ray sources of an electric field emission method using a nanostructure material electric field emission emitter, such as a carbon nanotube. 
         [0029]    If each of the rows of the X-ray sources  123  and  124  forms an arc shape, as shown in  FIG. 3 , when viewed from the front of the X-ray generation unit  120 , a plurality of X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n,    124 - 1 ,  124 - 2 ,  124 - n  is crisscross arranged in zigzags with respect to the specimen BR in two rows having different distances from the specimen. 
         [0030]    Specifically, when viewed from the front of the X-ray source generation unit  120 , assuming that the number of X-ray sources  123  and  124  is 2n, for convenience sake, the 2n X-ray sources  123  and  124  forms two rows each including the n X-ray sources. In this case, the n X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  are arranged in a first row along an arc placed at a first distance R 1  from the specimen BR. The remaining n X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  are arranged in a second row along an arc placed at a second distance R 2  from the specimen BR, which is greater than the first distance R 1 . In this case, it is preferred that the X-ray sources  123  of the first row are spaced apart from each other to the extent that they do not interfere with or hinder X-rays radiated by the X-ray sources  124  of the second row. 
         [0031]    Accordingly, the n X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  forming the first row and the remaining n X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  forming the second row are spaced apart from each other at a specific angular interval Δθ. Accordingly, all the X-ray sources  123  and  124  may radiate X-rays to the specimen BR at different angles. 
       Second Embodiment 
       [0032]      FIGS. 4( a ) and 4( b )  are a front view and plan view of the X-ray generation unit shown in  FIG. 2 . In accordance with the second embodiment of the present invention shown in  FIG. 4 , when viewed from the top of the X-ray generation unit  120 , the X-ray generation unit  120  includes a plurality of X-ray sources  125  and  126  arranged to form at least two rows and a mounting unit  122  for detachably installing the plurality of X-ray sources  125  and  126  on the X-ray generation unit  120 . 
         [0033]    As shown in  FIG. 4( a ) , it is preferred that the X-ray sources  125  and  126  form the same arc shape back and forth when viewed from the front of the X-ray generation unit  120 , but is not limited thereto. The X-ray sources  125  and  126  may form a straight line form. 
         [0034]    As shown in  FIG. 4( b ) , when viewed from the top of the X-ray generation unit  120 , X-ray sources  125 - 1 ,  125 - 2 , . . . ,  125 - n  and  126 - 1 ,  126 - 2 , . . . ,  126 - n  are crisscross arranged in zigzags back and forth with respect to the specimen BR in at least two rows. 
         [0035]    Specifically, assuming that the number of X-ray sources  125  and  126  is 2n, the two n X-ray sources  125  and  126  form two rows each including the n X-ray sources, the n X-ray sources  125 - 1 ,  125 - 2 , . . . ,  125 - n  arranged in a first row along an arc having a specific radius R from the specimen BR. The remaining n X-ray sources  126 - 1 ,  126 - 2 , . . . ,  126 - n  are arranged in a second row along an arc having the same radius R from the specimen BR. The first row is spaced apart from the second row at a specific interval I in the direction from the X-ray generation unit  120  to the device body  110 , when viewed from the top of the X-ray generation unit  120 . 
         [0036]    Furthermore, the n X-ray sources  125 - 1 ,  125 - 2 , . . . ,  125 - n  forming the first row and the remaining n X-ray sources  126 - 1 ,  126 - 2 , . . . ,  126 - n  forming the second row are spaced apart from each other at a specific angular interval A with respect to the specimen BR. Accordingly, all the X-ray sources  125  and  126  may radiate X-rays to the specimen BR at different angles. 
       Third Embodiment 
       [0037]      FIGS. 5( a ) and 5( b )  are a front view and plan view of the X-ray generation unit shown in  FIG. 2 . In accordance with the third embodiment of the present invention shown in  FIG. 5 , the X-ray generation unit  120  includes a plurality of X-ray sources  127  and  128  arranged to at least two rows and a mounting unit  122  for detachably installing the X-ray sources  127  and  128  on the X-ray generation unit  120 . 
         [0038]    When viewed from the front of the X-ray generation unit  120 , a plurality of X-ray sources  127 - 1 ,  127 - 2 , . . . ,  127 - n  and  128 - 1 ,  128 - 2 , . . . ,  128 - n  is crisscross arranged in zigzags in at least two rows having different distances from the specimen BR, as shown in  FIG. 5( a ) . Even when viewed from the top of the X-ray generation unit  120 , the plurality of X-ray sources  127 - 1 ,  127 - 2 , . . . ,  127 - n  and  128 - 1 ,  128 - 2 , . . . ,  128 - n  is crisscross arranged in zigzags in the at least two rows back and forth with respect to the specimen BR, as shown in  FIG. 5( b ) . 
         [0039]    Specifically, assuming that the number of X-ray sources  127  and  128  is 2n, the two n X-ray sources  127  and  128  form two rows each including the n X-ray sources, when viewed from the front of the X-ray generation unit  120 . The n X-ray sources  127 - 1 ,  127 - 2 , . . . ,  127 - n  are arranged in a first row along an arc placed in a first distance R 1  from the specimen BR. The remaining n X-ray sources  128 - 1 ,  128 - 2 , . . . ,  128 - n  are arranged in a second row along an arc placed at a second distance R 2  from the specimen BR, which is greater than the first distance R 1 . At the same time, even when viewed from the top of the X-ray generation unit  120 , the second row is spaced apart from the first row at a specific interval I in the direction from the X-ray generation unit  120  to the device body  110 . 
         [0040]    In accordance with the array structure of the X-ray sources  127  and  128  according to the third embodiment, X-rays radiated by the X-ray sources  128 - 1 ,  128 - 2 , . . . ,  128 - n  of the second row reach the specimen BR without interference or hindrance from the X-ray sources  127 - 1 ,  127 - 2 , . . . ,  127 - n  of the first row because the second row is spaced apart from the first row at the specific interval I when viewed from the top of the X-ray generation unit  120 . 
         [0041]    Accordingly, the plurality of X-ray sources  127  and  128  can be more densely arranged within the X-ray source generation unit  120  because an angular interval A8 between the X-ray sources  127  and  128  can be reduced to the fullest. As a result, a sharp high-resolution three-dimensional synthesis image can be obtained. 
       Fourth Embodiment 
       [0042]      FIGS. 6( a ) and 6( b )  are a front view and plan view of the X-ray generation unit shown in  FIG. 2 . The fourth embodiment shown in  FIG. 6  is a modified example of the first embodiment, and differences between the fourth embodiment and the first embodiment are chiefly described. The X-ray image obtaining apparatus  100  further includes moving means M for moving the X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  of at least one of a first row and a second row so that the X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  of the first row are spaced apart from the X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  of the second row at a specific interval I, when viewed from the top of the X-ray source generation unit  120 . 
         [0043]    In this case, it is preferred that the moving means M is a linear motor capable of moving the X-ray sources  123  of at least one of the first row and the second row, but may include a rotary motor. 
         [0044]    Various methods may be applied to the X-ray generation unit  120  according to the fourth embodiment depending on purposes. However, for example, in the state in which the first row and the second row have overlapped up and down when viewed from the top of the X-ray source generation unit  120 , a first driving method in which the X-ray sources of the first and the second rows sequentially radiate X-rays alternately or the X-ray sources of the first or the second row first sequentially radiate X-rays and the X-ray sources of the other row then sequentially radiate X-rays is possible. In this case, interference or hindrance may be present between the X-ray sources of the first and the second rows depending on the number of X-ray sources, etc. For another example, in the state in which the first row and the second row have overlapped up and down when viewed from the top of the X-ray source generation unit  120 , a second driving method in which the X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  of the first row first sequentially radiate X-rays toward the specimen BR, the X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  of the first row are moved to a location spaced apart from the X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  of the second row at a specific interval I, the X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  of the second row sequentially radiate X-rays toward the specimen BR, and the X-ray sources  123 - 1 ,  123 - 2 , . . . ,  123 - n  of the first row are then returned to the original location is possible. 
         [0045]    In accordance with the second driving method of the fourth embodiment, as in the third embodiment, the X-ray sources  123  belonging to the first row are spaced apart from the second row at the specific interval I when viewed from the top of the X-ray generation unit  120  and are moved. Accordingly, X-rays radiated by the X-ray sources  124 - 1 ,  124 - 2 , . . . ,  124 - n  forming the second row reach the specimen BR without interference or hindrance from the X-ray sources  127 - 1 ,  127 - 2 , . . . ,  127 - n  forming the first row. Accordingly, the X-ray sources  123  and  124  can be arranged more densely within the X-ray source generation unit  120  because an angular interval A between the X-ray sources  123  and  124  can be reduced to the fullest. Furthermore, unlike in the third embodiment, in the fourth embodiment, when three-dimensional stereoscopic images are synthesized, it is not necessary to correct a difference between images attributable to the interval I between the first row and the second row. Accordingly, a sharper high-resolution three-dimensional synthesis image can be obtained. 
         [0046]    In the preferred embodiments described so far, the plurality of X-ray sources has been illustrated as being arranged in 2 rows, but is not limited thereto. The plurality of X-ray sources may be arranged in 3 rows or 4 rows or more rows. 
         [0047]    Although a specific X-ray source malfunctions, a high-resolution three-dimensional synthesis image can be obtained without a problem by performing photographing using only the X-ray sources of other rows other than a corresponding row or by replacing the fail specific X-ray source with an adjacent another X-ray source of an adjacent another row, performing photographing, and then correcting an image. 
         [0048]    The X-ray generation unit  120  may be detachably installed on the device body  110 , the mounting unit  122  may be detachably installed on the X-ray generation unit  120 , and the X-ray sources may be detachably installed on the mounting unit  122 . Accordingly, a user can selectively install the mounting unit, having various patterns (e.g., the interval between the X-ray sources and the distribution, array, etc. of the X-ray sources), on the X-ray generation unit  120  according to a photographing purpose in response to required resolution and/or a different type of specimen, and can also easily replace and repair an X-ray source when it fails. 
         [0049]    Tomosynthesis photographing using the X-ray image obtaining apparatus  100  according to the first to the fourth embodiments of the present invention is described below. 
         [0050]    First, when a testee in a stand-up or standing state is in-situ placed at the photographing location of the X-ray image obtaining apparatus  100 , the device body  110  moves up and down along the row  111 , and thus the device body  110  is positioned so that the specimen BR is placed on the detector  130 . In this case, in order to prevent an abnormal portion within the specimen BR from being covered by a mammary gland tissue, etc., it is preferred that the specimen BR placed on the detector  130  is pressurized by a compression pad (not shown). 
         [0051]    Next, the plurality of X-ray sources sequentially operates for each row or sequentially operates while changing their rows and radiates X-rays to the specimen BR at different angles. The radiated X-rays pass through the specimen BR and are received by the detector  130 . The detector  130  generates an electrical signal for each location, which is proportional to the amount of the received incident X-rays, reads the electrical signals and location information, and obtains X-ray images of the specimen BR obtained at the respective angles by processing the read electrical signals and location information using an image processing algorithm. 
         [0052]    Thereafter, a high-resolution three-dimensional synthesis image can be obtained by synthesizing the X-ray images of the specimen BR obtained at the different angles using a tomosynthesis method well known to those skilled in the art to which the present invention pertains. 
         [0053]    The X-ray image obtaining apparatus according to the present invention can obtain a high-resolution three-dimensional tomosynthesis image and thus perform an accurate lesion diagnosis because X-ray photographing is rapidly performed on a specimen at various angles through the plurality of X-ray sources arranged according to a specific rule. 
         [0054]    Furthermore, reliability of a product is improved because a high-resolution three-dimensional tomosynthesis image can be obtained although some of the plurality of X-ray sources malfunction. 
         [0055]    Furthermore, the X-ray image obtaining apparatus according to the present invention does not generate any vibration and noise because it does not need to have additional movable parts for rotation driving. 
         [0056]    An example in which the X-ray image obtaining apparatus according to the present invention has been used as a mammography apparatus, that is, an X-ray apparatus for photographing the breast, has been described above, but the scope of the present invention is not limited to a device used for such a purpose. That is, the X-ray image obtaining apparatus of the present invention can be applied to all types of X-ray photographing apparatuses for obtaining projection images of a specimen using X-rays. 
         [0057]    Those skilled in the art to which the present invention pertains may easily understand that the technical scope of the present invention covers an X-ray photographing apparatus of such a type. Furthermore, the X-ray image obtaining apparatus of the present invention should be construed as covering all modifications or variations derived from the meaning and scope of the appended claims and their equivalents.