Patent Publication Number: US-2020275900-A1

Title: Diagnostic imaging apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The related application number 2016-163725, Diagnostic Imaging Apparatus, Aug. 24, 2016, Kazushige Tachibana, Atsushi Ohtani, and Tetsuro Mizuta, upon which this patent application is based, is hereby incorporated by reference. 
     FIELD 
     The present invention relates to a diagnostic imaging apparatus. 
     BACKGROUND 
     A diagnostic imaging apparatus including an imager that images a target to be imaged is known in general, as disclosed in International Publication No. 2011/125212, for example. 
     International Publication No. 2011/125212 discloses a PET apparatus that includes a whole-body PET (Positron Emission Tomography) apparatus including a whole-body PET detector that detects annihilation radiations, and a part-specific PET apparatus including a part-specific (head or breast) PET detector that detects annihilation radiations. In this PET apparatus, the part-specific PET apparatus corresponding to a specific part that requires detailed imaging is provided in the whole-body PET apparatus such that it is possible to image a wide range while imaging a specific part in detail. 
     However, in the PET apparatus described in International Publication No. 2011/125212, in order to image different specific parts in detail, separate part-specific PET apparatuses corresponding to imaging of the respective specific parts are required. Therefore, the number of components disadvantageously increases, and the apparatus structure disadvantageously becomes complex. 
     SUMMARY 
     The present invention has been proposed in order to solve the aforementioned problems, and an object of the present invention is to provide a diagnostic imaging apparatus in which an increase in the number of components and the complex apparatus structure can be significantly reduced or prevented. 
     In order to attain the aforementioned object, a diagnostic imaging apparatus according to an aspect of the present invention includes an imaging unit including an imager that images a target to be imaged, and a rotation mechanism that rotates the imaging unit to switch the imaging unit to a first state in which a first target area to be imaged of the target is imaged and a second state in which a second target area to be imaged of the target different from the first target area to be imaged is imaged. 
     As described above, the diagnostic imaging apparatus according to this aspect of the present invention includes the rotation mechanism that rotates the imaging unit to switch the imaging unit to the first state in which the first target area to be imaged of the target is imaged and the second state in which the second target area to be imaged of the target different from the first target area to be imaged is imaged. Accordingly, the imaging unit is rotated by the rotation mechanism such that the imaging unit can be switched to states in which different target areas to be imaged are imaged, and thus it is not necessary to provide a dedicated imaging unit for each target area to be imaged. Consequently, in the diagnostic imaging apparatus, an increase in the number of components and the complex apparatus structure can be significantly reduced or prevented. 
     In the aforementioned imaging apparatus according to this aspect, the imaging unit preferably further includes an imaging region in which the first target area to be imaged is placed in the first state and the second target area to be imaged is placed in the second state, and the imager preferably surrounds the imaging region. According to this structure, the first target area to be imaged or the second target area to be imaged placed in the imaging region can be reliably imaged by the imager that surround the imaging region. 
     The aforementioned diagnostic imaging apparatus according to this aspect preferably further includes a bed on which a human body as the target to be imaged is placed in a recumbent position, and the rotation mechanism preferably includes a rotary shaft that extends, in the imaging unit, in a short-side direction orthogonal to a longitudinal direction of the bed and about which the imaging unit is rotated. According to this structure, as compared with the case in which the rotary shaft extends in the longitudinal direction, an increase in the sizes of the rotary shaft and the rotation mechanism can be significantly reduced or prevented, and thus an increase in the size of the diagnostic imaging apparatus can be further significantly reduced or prevented. 
     In the aforementioned structure in which the rotation mechanism includes the rotary shaft, the imaging unit preferably further includes an imaging region in which a head of the human body in the recumbent position as the first target area to be imaged is placed in the first state and a breast of the human body in the recumbent position as the second target area to be imaged is placed in the second state, and the rotary shaft is preferably provided in a vicinity of an opening of the imaging region on a side opposite to the bed in the imaging unit in the first state. According to this structure, the rotary shaft is provided in the vicinity of the opening of the imaging region on the side opposite to the bed such that approach of the rotation range of the imaging unit to the bed can be significantly reduced or prevented, and thus inhibition of rotation of the imaging unit by the bed can be significantly reduced or prevented. Furthermore, the rotary shaft is provided in the vicinity of the opening of the imaging region such that the imaging region can be located within the narrow rotation range around the rotary shaft, and thus spacing apart of the imaging region from the bed can be significantly reduced or prevented. 
     In the aforementioned structure in which the rotation mechanism includes the rotary shaft, the imaging unit preferably further includes an imaging region in which a head of the human body in the recumbent position as the first target area to be imaged is placed in the first state and a breast of the human body in the recumbent position as the second target area to be imaged is placed in the second state, and the rotary shaft is preferably provided in a vicinity of an opening of the imaging region on the bed side in the imaging unit in the first state. According to this structure, the rotary shaft is provided in the vicinity of the opening of the imaging region on the bed side such that protrusion of a portion that supports the rotary shaft of the rotation mechanism to the side of the diagnostic imaging apparatus opposite to the bed can be significantly reduced or prevented, and thus an increase in the size of the diagnostic imaging apparatus can be significantly reduced or prevented. Furthermore, the rotary shaft is provided in the vicinity of the opening of the imaging region such that the imaging region can be located within the narrow rotation range around the rotary shaft, and thus spacing apart of the imaging region from the bed can be significantly reduced or prevented. 
     In the aforementioned structure in which the rotary shaft is provided in the vicinity of the opening of the imaging region, the rotary shaft is preferably provided at substantially a same height as that of an upper surface of the bed. According to this structure, the rotary shaft is provided at substantially the same height as that of the upper surface of the bed such that spacing apart of the imaging region from the upper surface of the bed can be significantly reduced or prevented as compared with the case in which the rotary shaft is provided at a height spaced apart from the upper surface of the bed. 
     The aforementioned structure further including the bed preferably further includes a headrest detachably attached to an end of the bed on the imaging unit side and that supports a head of the human body. According to this structure, when the headrest is attached to the end of the bed on the imaging unit side, the position of the headrest is adjusted such that the head of the recumbent human body can be placed at an appropriate position in the imaging region. Consequently, when the head of the recumbent human body is imaged as the target area to be imaged, the head of the recumbent human body can be easily imaged by the imager. Furthermore, the headrest is detached from the end of the bed on the imaging unit side such that it is possible to prevent the headrest from interfering with rotation of the imaging unit. 
     In the aforementioned structure further including the bed, the imaging unit preferably includes a support that extends in a direction away from the bed in the second state and supports the human body. Here, when the vicinity of the center of the human body such as the chest is imaged as the second target area to be imaged, a portion of the human body is located in a direction away from the bed relative to the imaging region of the imaging unit. Therefore, in the present invention, the support that extends in the direction away from the bed and supports the human body is provided in the imaging unit in the second state such that when the vicinity of the center of the human body is imaged as the second target area to be imaged, the recumbent human body can be supported by the support that extends in the direction away from the bed. Consequently, the human body can be securely kept in a recumbent position, and thus the second target area to be imaged can be stably imaged. 
     In the aforementioned diagnostic imaging apparatus according to this aspect, the first target area to be imaged is preferably a head of the human body in a supine position, the imager preferably surrounds the head of the human body within a vertical plane in the first state, the second target area to be imaged is preferably a breast of the human body in a prone position, and the imager preferably surrounds the breast of the human body within a horizontal plane in the second state. According to this structure, the head of the supine human body can be stably and reliably imaged. Furthermore, the breast of the human body can hang downward in a prone position, and thus a wide range of the breast of the human body can be stably and reliably imaged. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view showing the head imaging state of a PET apparatus according to a first embodiment. 
         FIG. 2  is a top view showing the head imaging state of the PET apparatus according to the first embodiment. 
         FIG. 3  is a side view showing the head imaging state of the PET apparatus according to the first embodiment, as viewed from the imaging unit side. 
         FIG. 4  is a block diagram of the PET apparatus according to the first embodiment. 
         FIG. 5  is a schematic sectional view showing the breast imaging state of the PET apparatus according to the first embodiment. 
         FIG. 6  is a top view showing the breast imaging state of the PET apparatus according to the first embodiment. 
         FIG. 7  is a side view showing the breast imaging state of the PET apparatus according to the first embodiment, as viewed from the imaging unit side. 
         FIG. 8  is a diagram illustrating the rotation operation of an imaging unit of the PET apparatus according to the first embodiment. 
         FIG. 9  is a diagram showing a state during rotation in the rotation operation of the imaging unit of the PET apparatus according to the first embodiment. 
         FIG. 10  is a diagram illustrating the rotation operation of the imaging unit of the PET apparatus according to the first embodiment. 
         FIG. 11  is a schematic sectional view showing the head imaging state of a PET apparatus according to a second embodiment. 
         FIG. 12  is a schematic sectional view showing the breast imaging state of the PET apparatus according to the second embodiment. 
         FIG. 13  is a schematic sectional view showing the chest imaging state of an X-ray imaging apparatus according to a third embodiment. 
         FIG. 14  is a schematic sectional view showing the breast imaging state of the X-ray imaging apparatus according to the third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention are hereinafter described with reference to the drawings. 
     First Embodiment 
     (Outline of PET Apparatus) 
     The structure of a PET apparatus  100  according to a first embodiment of the present invention is now described with reference to  FIGS. 1 to 7 . The PET apparatus  100  is an example of a “diagnostic imaging apparatus” in the claims. 
     The PET apparatus  100  is an apparatus that captures an image inside a human body T, using a drug labeled with a positron emitting nuclide. Specifically, the PET apparatus  100  acquires a position at which pair annihilation of the drug occurs by detecting a pair of gamma rays (radiations) generated by the pair annihilation of electrons and positrons of the drug. Furthermore, the PET apparatus  100  forms (captures) the image inside the human body T by acquiring a plurality of positions at which the pair annihilation of the drug occurs. The formed image is used in image diagnosis for determining the presence or absence of cancer cells, for example. The human body T is an example of a “target to be imaged” in the claims. 
     In the first embodiment, the PET apparatus  100  can switch between a head imaging state of imaging the head T 1  of the supine human body T and a breast imaging state of imaging the breast T 2  of the prone human body T. In the first embodiment, the structure of the PET apparatus  100  in the head imaging state shown in  FIGS. 1 to 3  is described first, and then points of the breast imaging state of the PET apparatus  100  shown in  FIGS. 5 to 7  different from the head imaging state are described. The head T 1  and the breast T 2  are examples of a “first target area to be imaged” and a “second target area to be imaged” in the claims, respectively. In addition, the head imaging state and the breast imaging state are examples of a “first state” and a “second state” in the claims, respectively. 
     (Structure of PET Apparatus (Head Imaging State)) 
     As shown in  FIGS. 1 to 3 , the PET apparatus  100  includes an imaging unit  1 , a bed  2  on which the human body T as a target to be imaged is placed in a recumbent position, and a rotation mechanism  3  that rotates the imaging unit  1 . As shown in  FIG. 4 , the PET apparatus  100  includes a controller  4  that controls the entire PET apparatus  100 , and an image processor  5  that creates an image based on a detection signal from the imaging unit  1 . 
     The imaging unit  1  is disposed on one side (X1 side) of the bed  2  in an X direction. Furthermore, as shown in  FIG. 3 , the imaging unit  1  includes a housing  10  and a plurality of (fourteen in the first embodiment) detectors  11  disposed inside the housing  10 . The detector  11  is an example of an “imager” in the claims. 
     In the housing  10 , as shown in  FIG. 1 , an imaging region  10   a  in which the target area to be imaged (the head T 1  or the breast T 2 ) of the human body T is placed is formed. The imaging region  10   a  includes a hole that passes through the housing  10 . In the head imaging state, the imaging region  10   a  passes through the housing  10  in the X direction, in which the bed  2  extends, in a horizontal direction. 
     A head support  10   b  is provided on the X1 side (the side opposite to the bed  2 ) of the housing  10 . In the head imaging state shown in  FIGS. 1 to 3 , the head support  10   b  extends downward from a corner of the housing  10  on the X1 side and on the lower side (Z2 side). Furthermore, the head support  10   b  has a plate shape. It should be noted that the head support  10   b  does not support the head T 1  of the human body T in the head imaging state shown in  FIGS. 1 to 3 . The head support  10   b  is an example of a “support” in the claims. 
     The detectors  11  detect (collect) the gamma rays generated by the pair annihilation of the drug and transmit a detection signal to the image processor  5  via the controller  4 . As shown in  FIG. 1 , in the head imaging state, each of the plurality of detectors  11  extends in the X direction over substantially the entire imaging region  10   a  that extends in the X direction. 
     As shown in  FIG. 3 , the plurality of detectors  11  surround the imaging region  10   a  inside the housing  10 . In the head imaging state, the plurality of detectors  11  surround the head T 1  of the supine human body T placed in the imaging region  10   a  within a vertical plane orthogonal to the X direction in which the imaging region  10   a  extends. Thus, the pair of gamma rays emitted in mutually opposite directions due to the pair annihilation of the drug can be reliably detected by a pair of detectors  11  that face each other. Consequently, the PET apparatus  100  acquires an internal image of the head T 1  by detecting (imaging) the gamma rays with the detectors  11 . 
     The bed  2  includes a top board  20  and a base  21  that supports the top board  20 . As shown in  FIG. 2 , the top board  20  has a rectangular shape, which is long in a longitudinal direction (X direction) in a plan view. On the upper surface  20   a  of the top board  20 , the human body T can lie in a recumbent position such as a prone position, a supine position, and a lateral recumbent position. As shown in  FIG. 1 , a headrest  22  is detachably attached to an end  20   b  of the top board  20  on the X1 side (imaging unit  1  side) in the longitudinal direction. The headrest  22  includes a support  22   a  that supports the head of the human body and a step  22   b . The support  22   a  of the headrest  22  is located above (Z1 side) the upper surface  20   a  of the top board  20  by a predetermined height due to the step  22   b . The headrest  22  is made of a material (carbon, for example) that does not absorb gamma rays. 
     The base  21  is disposed below the top board  20 . The base  21  moves the top board  20  in an upward-downward direction (Z direction) and the longitudinal direction (X direction) while maintaining the horizontal state of the upper surface  20   a  of the top board  20 . As shown in  FIG. 4 , the base  21  includes an upward-downward drive  21   a  and a horizontal drive  21   b . The upward-downward drive  21   a  or the horizontal drive  21   b  of the base  21  is driven by the controller  4  such that the top board  20  is moved in the upward-downward direction or the X direction. Thus, in the head imaging state, the top board  20  can be moved in the X direction in a state in which the human body T is lying in the recumbent position (supine position) on the top board  20  such that the head T 1  of the human body T is placed at a desired position in the imaging region  10   a . In addition, the head T 1  is imaged in a supine position by the PET apparatus  100 , and thus the head T 1  can be imaged in a stably fixed state. Thus, a clear image of the head T 1  can be obtained. 
     As shown in  FIGS. 1 to 3 , the rotation mechanism  3  includes a rotary shaft  30  that rotates the imaging unit  1 , a pair of support walls  31  that support the imaging unit  1  via the rotary shaft  30 , and a rotational drive  32  (see  FIG. 4 ) that rotates the rotary shaft  30 . As shown in FIG.  1 , the rotary shaft  30  is disposed proximally below an opening  10   c  of the imaging region  10   a  on the X1 side in the head imaging state. In addition, the rotary shaft  30  is disposed at substantially the same position (height) as that of the upper surface  20   a  of the top board  20  in the upward-downward direction. As shown in  FIGS. 2 and 3 , the rotary shaft  30  passes through the housing  10  in a short-side direction (Y direction) orthogonal to the longitudinal direction. 
     The pair of support walls  31  sandwich the imaging unit  1  in the short-side direction. The support walls  31  extend in the upward-downward direction. 
     In the first embodiment, the rotation mechanism  3  rotates the imaging unit  1  in the head imaging state shown in  FIGS. 1 to 3  about the rotary shaft  30  by about 90 degrees in a clockwise direction (a rotational direction in which the head support  10   b  is away from the bed  2 ) R1 from a state in a side view in  FIG. 1  so as to switch the imaging unit  1  to the breast imaging state shown in  FIGS. 5 to 7 . Furthermore, the rotation mechanism  3  rotates the imaging unit  1  in the breast imaging state shown in  FIGS. 5 to 7  about the rotary shaft  30  by about 90 degrees in a counterclockwise direction (a rotational direction in which the head support  10   b  moves downward) R2 from a state in a side view in  FIG. 5  so as to switch the imaging unit  1  to the head imaging state shown in  FIGS. 1 to 3 . 
     (Structure of PET Apparatus (Breast Imaging State)) 
     As a result, in the breast imaging state shown in  FIGS. 5 to 7 , the imaging unit  1  in the head imaging state shown in  FIGS. 1 to 3  is rotated by about 90 degrees. Specifically, in the breast imaging state, the imaging region  10   a  of the imaging unit  1  extends in the upward-downward direction (Z direction) orthogonal to the upper surface  20   a  of the top board  20  of the bed  2 , and passes through the housing  10 , as shown in  FIG. 5 . Thus, in the PET apparatus  100 , the breast T 2  of the prone human body T can be placed in a hanging state within the imaging region  10   a.    
     In the breast imaging state, as shown in  FIG. 6 , the plurality of detectors  11  of the imaging unit  1  surround the breast T 2  of the prone human body T placed in the imaging region  10   a  within a horizontal plane orthogonal to the Z direction in which the imaging region  10   a  extends. Consequently, the PET apparatus  100  acquires an internal image of the breast T 2  by detecting (imaging) the gamma rays with the detectors  11 . 
     In the breast imaging state, a support surface  10   d  of the housing  10  of the imaging unit  1  is located slightly above (Z1 side) the upper surface  20   a  of the bed  2 , as shown in  FIG. 5 . The support surface  10   d  is a surface located on the X1 side in the head imaging state shown in  FIGS. 1 to 3 . In the breast imaging state, the head support  10   b  extends from the support surface  10   d  toward the X1 side away from the bed  2 . Thus, the head T 1  and the upper portion of the prone human body T are supported by the head support  10   b  and the support surface  10   d.    
     In the breast imaging state, each of the plurality of detectors  11  extends in the Z direction over substantially the entire imaging region  10   a  that extends in the Z direction. Furthermore, in the breast imaging state, the headrest  22  is detached from the top board  20 . Thus, a portion of the breast T 2  of the prone human body T corresponding to the height of the headrest  22  is prevented from failing to be placed within the imaging region  10   a . In the breast imaging state, the rotary shaft  30  is disposed on the X1 side in the vicinity of the opening  10   c  of the imaging region  10   a  on the Z1 side. The rotation mechanism  3  can maintain the state (either the head imaging state or the breast imaging state) of the imaging unit  1  with a fixing mechanism (not shown). 
     (Rotation Operation) 
     The rotation operation of the imaging unit  1  of the PET apparatus  100  according to the first embodiment is now specifically described with reference to  FIGS. 1, 5, and 8 to 10 . 
     In the case of the imaging unit  1  of the PET apparatus  100  in the head imaging state shown in  FIG. 1 , the horizontal drive  21   b  (see  FIG. 4 ) is driven by the controller  4  (see  FIG. 4 ) in a state in which the human body T is not placed on the bed  2 , as shown in  FIG. 8 . Thus, the top board  20  of the bed  2  is moved toward the X2 side away from the imaging unit  1 . At this time, the top board  20  is moved toward the X2 side at least to a position at which the housing  10  of the imaging unit  1  does not contact the top board  20  during rotation. Then, the headrest  22  is detached from the end  20   b  of the top board  20  on the X1 side. 
     Thereafter, as shown in  FIG. 9 , the controller  4  drives the rotational drive  32  (see  FIG. 4 ) to rotate the imaging unit  1  about the rotary shaft  30  by about 90 degrees in the R1 direction. Thus, the imaging region  10   a  is switched from a state of extending in the X direction to a state of extending in the Z direction. Finally, the controller  4  drives the horizontal drive  21   b  to move the top board  20  of the bed  2  to the X1 side toward the imaging unit  1 . Thus, the imaging unit  1  is switched to the breast imaging state shown in  FIG. 5 . Thereafter, the top board  20  is appropriately moved in the X direction such that the head T 1  of the supine human body T is placed at a desired position in the imaging region  10   a.    
     When the imaging unit  1  of the PET apparatus  100  is switched from the breast imaging state shown in  FIG. 5  to the head imaging state shown in  FIG. 1 , an operation opposite to the above switching is performed. That is, in the case of the imaging unit  1  in the breast imaging state shown in  FIG. 5 , the controller  4  drives the horizontal drive  21   b  in a state in which the human body T is not placed on the bed  2 , as shown in  FIG. 10 . Thus, the top board  20  of the bed  2  is moved toward the X2 side away from the imaging unit  1 . At this time, the top board  20  is moved toward the X2 side at least to a position at which the housing  10  of the imaging unit  1  does not contact the top board  20  during rotation. 
     Thereafter, as shown in  FIG. 9 , the controller  4  drives the rotational drive  32  to rotate the imaging unit  1  about the rotary shaft  30  by about 90 degrees in the R2 direction. Thus, the imaging region  10   a  is switched from a state of extending in the Z direction to a state of extending in the X direction. Then, the headrest  22  is attached to the end  20   b  of the top board  20  on the X1 side. Finally, the controller  4  drives the horizontal drive  21   b  to move the top board  20  of the bed  2  to the X1 side toward the imaging unit  1 . Thus, the imaging unit  1  is switched to the head imaging state shown in  FIG. 1 . Thereafter, the human body T is placed in a prone position on the top board  20 , the head support  10   b , and the support surface  10   d  such that the breast T 2  hangs downward within the imaging region  10   a.    
     Advantageous Effects of First Embodiment 
     According to the first embodiment, the following advantageous effects are achieved. 
     According to the first embodiment, as described above, the PET apparatus  100  includes the rotation mechanism  3  that rotates the imaging unit  1  to switch the imaging unit  1  to the head imaging state in which the head T 1  of the human body T is imaged and the breast imaging state in which the breast T 2  of the human body T different from the head T 1  is imaged. Accordingly, the imaging unit  1  is rotated by the rotation mechanism  3  such that the imaging unit  1  can be switched to states in which different target areas to be imaged are imaged, and thus it is not necessary to provide a dedicated imaging unit for each area of the human body T. Consequently, in the PET apparatus  100 , an increase in the number of components and the complex apparatus structure can be significantly reduced or prevented, and the installation cost of the PET apparatus  100  can be reduced. 
     According to the first embodiment, as described above, the detectors  11  surround the imaging region  10   a  in which the head T 1  is placed in the head imaging state and the breast T 2  is placed in the breast imaging state. Accordingly, the head T 1  or the breast T 2  placed in the imaging region  10   a  can be reliably imaged by the detectors  11  that surround the imaging region  10   a.    
     According to the first embodiment, as described above, the rotary shaft  30  of the rotation mechanism  3  about which the imaging unit  1  is rotated extends, in the imaging unit  1 , in the short-side direction (Y direction) orthogonal to the longitudinal direction (X direction) of the top board  20  of the bed  2 . Here, when the rotary shaft  30  extends in the longitudinal direction, it is necessary to dispose the support walls  31  of the rotary shaft  30  disposed on the X1 side of the top board  20  so as not to interfere with the top board  20 , and thus it is believed that the rotary shaft  30  and the rotation mechanism  3  are increased in size accordingly. Thus, as compared with the case in which the rotary shaft  30  extends in the longitudinal direction, an increase in the sizes of the rotary shaft  30  and the rotation mechanism  3  can be significantly reduced or prevented, and thus an increase in the size of the PET apparatus  100  can be further significantly reduced or prevented. 
     According to the first embodiment, as described above, the rotary shaft  30  is provided in the vicinity of the opening  10   c  of the imaging region  10   a  on the side (X1 side) opposite to the bed  2  in the imaging unit  1  in the head imaging state. Accordingly, approach of the rotation range of the imaging unit  1  to the bed  2  can be significantly reduced or prevented, and thus inhibition of rotation of the imaging unit  1  by the bed  2  can be significantly reduced or prevented. Furthermore, the rotary shaft  30  is provided in the vicinity of the opening  10   c  of the imaging region  10   a  such that the imaging region  10   a  can be located within the narrow rotation range around the rotary shaft  30 , and thus spacing apart of the imaging region  10   a  from the bed  2  can be significantly reduced or prevented. 
     According to the first embodiment, as described above, the rotary shaft  30  is provided at substantially the same height as that of the upper surface  20   a  of the bed  2 . Accordingly, the rotary shaft  30  is provided in the vicinity of the opening  10   c  of the imaging region  10   a  and at substantially the same height as that of the upper surface  20   a  of the bed  2  such that spacing apart of the imaging region  10   a  from the upper surface  20   a  of the bed  2  can be significantly reduced or prevented as compared with the case in which the rotary shaft  30  is provided at a height spaced apart from the upper surface  20   a  of the bed  2 . 
     According to the first embodiment, as described above, the PET apparatus  100  includes the headrest  22  detachably attached to the end  20   b  of the bed  2  on the imaging unit  1  side (X1 side) and that supports the head T 1  of the human body T. Accordingly, when the headrest  22  is attached to the end  20   b  of the bed  2  on the X1 side, the position of the headrest  22  is adjusted such that the head T 1  of the recumbent (supine) human body T can be placed at an appropriate position in the imaging region  10   a . Consequently, in the head imaging state, the head T 1  of the recumbent human body T can be easily imaged by the detectors  11 . Furthermore, the headrest  22  is detached from the end of the bed  2  on the X1 side such that it is possible to prevent the headrest  22  from interfering with rotation of the imaging unit  1 . 
     According to the first embodiment, as described above, the head support  10   b  that supports the head T 1  of the human body T extends, in the imaging unit  1 , in the direction (X1 side) away from the bed  2  in the breast imaging state. Accordingly, in the breast imaging state in which the breast T 2  located in the vicinity of the center of the human body T in the longitudinal direction is imaged, the head T 1  of the recumbent (prone) human body T can be supported by the head support  10   b  that extends in the direction away from the bed  2 . Consequently, the human body T can be securely kept in a recumbent position, and thus the breast T 2  can be stably imaged. 
     According to the first embodiment, as described above, in the PET apparatus  100 , the plurality of detectors  11  surround the head T 1  of the human body T within the vertical plane in the head imaging state. Accordingly, the head T 1  of the supine human body T can be stably and reliably imaged. 
     According to the first embodiment, as described above, in the PET apparatus  100 , the plurality of detectors  11  surround the breast T 2  of the human body T within the horizontal plane in the breast imaging state. Accordingly, the breast T 2  of the human body T can hang downward in a prone position, and thus a wide range of the breast T 2  of the human body T can be stably and reliably imaged. In  FIG. 6 , both the breasts T 2  of the human body T are surrounded by the plurality of detectors  11 , but only one breast may be surrounded by the plurality of detectors  11 . 
     Second Embodiment 
     The structure of a PET apparatus  200  according to a second embodiment of the present invention is now described with reference to  FIGS. 11 and 12 . In the second embodiment, a rotary shaft  130  is provided on the bed  2  side in a head imaging state unlike the first embodiment. The same structures as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The PET apparatus  200  is an example of a “diagnostic imaging apparatus” in the claims. 
     (Structure of PET Apparatus (Head Imaging State)) 
     As shown in  FIG. 11 , the PET apparatus  200  includes an imaging unit  101 , a bed  2 , and a rotation mechanism  103  that rotates the imaging unit  101 . The imaging unit  101  includes a housing  110  and a plurality of detectors  111  disposed inside the housing  110 . The detectors  111  are examples of an “imager” in the claims. 
     In the head imaging state, a head support  110   b  is provided on the X2 side (the bed  2  side) of the housing  110 . In the head imaging state shown in  FIG. 11 , the head support  110   b  extends upward from a corner of the housing  110  on the X2 side and the upper side (Z1 side). Furthermore, the head support  110   b  has a plate shape. It should be noted that the head support  110   b  does not support the head T 1  of a human body T in the head imaging state. The head support  110   b  is an example of a “support” in the claims. 
     Unlike the detectors  11  according to the first embodiment, the plurality of detectors  111  extend in an X direction from the vicinity of an opening  110   c  on the X2 side, into which the head T 1  is inserted, of an imaging region  10   a  that extends in the X direction to the vicinity of the center of the imaging region  10   a  in the head imaging state, but are not provided in the vicinity of an opening  110   e  of the imaging region  10   a  on the X1 side. 
     The rotation mechanism  103  includes the rotary shaft  130  in place of the rotary shaft  30  according to the first embodiment. In the head imaging state, the rotary shaft  130  is disposed proximally below the opening  110   c  of the imaging region  10   a  on the X2 side. In addition, the rotary shaft  130  is disposed at substantially the same position (height) as that of the upper surface  20   a  of a top board  20  in an upward-downward direction. 
     In the second embodiment, the rotary mechanism  103  rotates the imaging unit  101  in the head imaging state shown in  FIG. 11  about the rotary shaft  130  by about 90 degrees in a counterclockwise direction (a rotational direction in which the head support  110   b  is away from the bed  2 ) R11 from a state in a side view in  FIG. 11  so as to switch the imaging unit  101  to a breast imaging state shown in  FIG. 12 . Furthermore, the rotary mechanism  103  rotates the imaging unit  101  in the breast imaging state shown in  FIG. 12  about the rotary shaft  130  by about 90 degrees in a clockwise direction (a rotational direction in which the head support  110   b  moves upward) R12 from a state in a side view in  FIG. 12  so as to switch the imaging unit  101  to the head imaging state shown in FIG.  11 . That is, in the PET apparatus  200  according to the second embodiment, the state of the imaging unit  101  is switched as the imaging unit  101  rotates in a direction opposite to the rotational direction of the imaging unit  1  according to the first embodiment. 
     (Structure of PET Apparatus (Breast Imaging State)) 
     In the breast imaging state shown in  FIG. 12 , the imaging unit  101  in the head imaging state shown in  FIG. 11  is rotated by about 90 degrees. Specifically, in the breast imaging state, the detectors  111  extend in a Z direction from the vicinity of the opening  110   c  on the Z1 side, into which a breast T 2  is inserted, of the imaging region  10   a  that extends in the Z direction to the vicinity of the center of the imaging region  10   a , unlike the detectors  11  according to the first embodiment. Consequently, in order to image the head T 1  or the breast T 2 , the detectors  111  may not be disposed in the vicinity of the opening  110   e  into which the head T 1  or the breast T 2  is not inserted as long as the detectors  111  are disposed in the vicinity of the opening  110   c  into which the head T 1  or the breast T 2  is inserted. Thus, the detectors  111  can be downsized, and thus it is possible to reduce the cost of the detectors  111  and to increase the degree of freedom of arrangement of the remaining members in the imaging unit  101 . 
     In the second embodiment, the PET apparatus  200  has the same positional relationship as that of the PET apparatus  100  in the breast imaging state according to the first embodiment, except for the detectors  111 , when the imaging unit  101  in the head imaging state rotates in the direction R11 opposite to the rotational direction R1 of the imaging unit  1  according to the first embodiment. The remaining structures of the PET apparatus  200  according to the second embodiment are similar to those of the PET apparatus  100  according to the first embodiment. Furthermore, the rotation operation of the PET apparatus  200  according to the second embodiment is the same as that of the PET apparatus  100  according to the first embodiment except that the rotational direction at the time of switching is reversed, and thus description thereof is omitted. 
     Advantageous Effects of Second Embodiment 
     According to the second embodiment, the following advantageous effects are achieved. 
     According to the second embodiment, as described above, the PET apparatus  200  includes the rotary mechanism  103  that rotates the imaging unit  101  so as to switch the imaging unit  101  to the head imaging state in which the head T 1  of the human body T is imaged and the breast imaging state in which the breast T 2  of the human body T different from the head T 1  is imaged. Accordingly, similarly to the first embodiment, in the PET apparatus  200 , an increase in the number of components and the complex apparatus structure can be significantly reduced or prevented. 
     According to the second embodiment, as described above, the rotary shaft  130  is provided in the vicinity of the opening  110   c  of the imaging region  10   a  on the bed  2  side (X2 side) in the imaging unit  101  in the head imaging state. Accordingly, protrusion of support walls  31  of the rotation mechanism  103  to the side (X1 side) of the PET apparatus  200  opposite to the bed  2  can be significantly reduced or prevented, and thus an increase in the size of the PET apparatus  200  can be significantly reduced or prevented. Furthermore, the rotary shaft  130  is provided in the vicinity of the opening  110   c  of the imaging region  10   a  such that the imaging region  10   a  can be located within the narrow rotation range around the rotary shaft  130 , and thus spacing apart of the imaging region  10   a  from the bed  2  can be significantly reduced or prevented. 
     According to the second embodiment, as described above, the detectors  111  extend in the Z direction from the vicinity of the opening  110   c  on the Z1 side, into which the breast T 2  is inserted, of the imaging region  10   a  that extends in the Z direction to the vicinity of the center of the imaging region  10   a  in the breast imaging state. Accordingly, the detectors  111  can be downsized, and thus it is possible to reduce the cost of the detectors  111  and to increase the degree of freedom of arrangement of the remaining members in the imaging unit  101 . The remaining advantageous effects of the second embodiment are similar to those of the first embodiment. 
     Third Embodiment 
     The structure of an X-ray imaging apparatus  300  according to a third embodiment of the present invention is now described with reference to  FIGS. 13 and 14 . In the third embodiment, the X-ray imaging apparatus  300  images a human body T in a standing position unlike the first embodiment. The X-ray imaging apparatus  300  is an example of a “diagnosis imaging apparatus” in the claims. 
     (Outline of X-ray Imaging Apparatus) 
     The X-ray imaging apparatus  300  is an apparatus that captures an image (simple X-ray image) inside the human body T, utilizing the fact that the degree of X-ray absorption in the body is different. The image formed in the X-ray imaging apparatus  300  is used for image diagnosis. 
     In the third embodiment, the X-ray imaging apparatus  300  can switch between a chest imaging state in which the chest T 3  of the standing human body T is imaged and a breast imaging state in which the breast T 2  of the standing human body T is imaged. In the third embodiment, the structure of the X-ray imaging apparatus  300  in the chest imaging state shown in  FIG. 13  is described first, and then points of the breast imaging state of the X-ray imaging apparatus  300  shown in  FIG. 14  different from the chest imaging state are described. The chest T 3  and the chest imaging state are examples of a “first target area to be imaged” and a “first state” in the claims, respectively. 
     (Structure of X-ray Imaging Apparatus (Chest Imaging State)) 
     As shown in  FIG. 13 , the X-ray imaging apparatus  300  includes an imaging unit  201  and a rotation mechanism  203  that rotates the imaging unit  201 . The X-ray imaging apparatus  300  further includes a controller (not shown) that totally controls the X-ray imaging apparatus  300  and an image processor (not shown) that creates an image based on a detection signal from the imaging unit  201 . 
     The imaging unit  201  includes a housing  210  and an imager  211  disposed inside the housing  210 . At the center of the housing  210 , an imaging region  210   a  in which the target area to be imaged (the chest T 3  or the breast T 2 ) of the human body T is placed is formed. The imaging region  210   a  includes a hole that passes through the housing  210 . In the chest imaging state shown in  FIG. 13 , the imaging region  210   a  passes through the housing  210  so as to extend in an upward-downward direction (Z direction). 
     The imager  211  includes an X-ray source  211   a  that radiates X-rays in a predetermined direction (W direction) in which the imaging region  210   a  is located in the chest imaging state, and an X-ray detector  211   b  that faces the X-ray source  211   a  in the W direction and detects the X-rays. In other words, the X-ray source  211   a  and the X-ray detector  211   b  sandwich the imaging region  210   a  in the W direction. Consequently, the X-ray imaging apparatus  300  acquires an internal image of the chest T 3  placed in the imaging region  210   a.    
     The rotation mechanism  203  includes a rotary shaft  230  that rotates the imaging unit  201 , support walls  231  that support the imaging unit  201  via the rotary shaft  230 , and a lifting mechanism  233  that moves the support walls  231  in the upward-downward direction (Z direction). The lifting mechanism  233  is disposed below (Z2 side) the support walls  231 . Furthermore, the imaging unit  201  is rotated about the rotary shaft  230  by a rotational drive (not shown). 
     In the third embodiment, the rotation mechanism  203  rotates the imaging unit  201  in the chest imaging state shown in  FIG. 13  about the rotary shaft  230  by about 90 degrees in a counterclockwise direction R21 from a state in a side view in  FIG. 13  so as to switch the imaging unit  201  to the breast imaging state shown in  FIG. 14 . Furthermore, the rotation mechanism  203  rotates the imaging unit  201  in the breast imaging state shown in  FIG. 14  about the rotary shaft  230  by about 90 degrees in a clockwise direction R22 from a state in a side view in  FIG. 14  so as to switch the imaging unit  201  to the chest imaging state shown in  FIG. 13 . 
     (Structure of X-ray Imaging Apparatus (Breast Imaging State)) 
     In the breast imaging state shown in  FIG. 14 , the imaging unit  201  in the chest imaging state shown in  FIG. 13  is rotated by about 90 degrees. Specifically, in the breast imaging state, the imaging region  210   a  of the imaging unit  201  passes through the housing  210  so as to extend in the W direction. In the breast imaging state, the X-ray source  211   a  and the X-ray detector  211   b  sandwich the imaging region  210   a  in the upward-downward direction (Z direction). Thus, the imager  211  images the breast T 2  of the standing human body T placed in the imaging region  210   a  while sandwiching the breast T 2  in the upward-downward direction. 
     (Rotation Operation) 
     The rotation operation of the imaging unit  201  of the X-ray imaging apparatus  300  according to the third embodiment is now specifically described with reference to  FIGS. 13 and 14 . 
     The imaging unit  201  of the X-ray imaging apparatus  300  in the chest imaging state shown in  FIG. 13  is rotated about the rotary shaft  230  by about 90 degrees in the R21 direction. Thus, the imaging region  210   a  is switched from a state of extending in the Z direction to a state of extending in the W direction. Finally, the positions of the support walls  231  in the upward-downward direction are adjusted by the lifting mechanism  233  such that in the upward-downward direction, the height of the imaging region  210   a  is matched to the height of the breast T 2  of the standing human body T. Thus, the imaging unit  201  of the X-ray imaging apparatus  300  is switched to the breast imaging state shown in  FIG. 14 . 
     When the imaging unit  201  of the X-ray imaging apparatus  300  is switched from the breast imaging state shown in  FIG. 14  to the chest imaging state shown in  FIG. 13 , an operation opposite to the above switching is performed. That is, in the X-ray imaging apparatus  300  in the breast imaging state shown in  FIG. 14 , the imaging unit  201  is rotated about the rotary shaft  230  by about 90 degrees in the R22 direction. Thus, the imaging region  210   a  is switched from a state of extending in the W direction to a state of extending in the Z direction. Finally, the positions of the support walls  231  in the upward-downward direction are adjusted by the lifting mechanism  233  such that in the upward-downward direction, the height of the imaging region  210   a  is matched to a height at which the chest T 3  of the standing human body T is imaged. Thus, the X-ray imaging apparatus  300  is switched to the chest imaging state shown in  FIG. 13 . 
     Advantageous Effects of Third Embodiment 
     According to the third embodiment, the following advantageous effects are achieved. 
     According to the third embodiment, as described above, the X-ray imaging apparatus  300  includes the rotation mechanism  203  that rotates the imaging unit  201  to switch the imaging unit  201  to the chest imaging state in which the chest T 3  of the human body T is imaged and the breast imaging state in which the breast T 2  of the human body T different from the chest T 3  is imaged. Accordingly, similarly to the first embodiment, in the X-ray imaging apparatus  300 , an increase in the number of components and the complex apparatus structure can be significantly reduced or prevented. 
     Modified Examples 
     The embodiments disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is not shown by the above description of the embodiments but by the scope of claims for patent, and all modifications (modified examples) within the meaning and scope equivalent to the scope of claims for patent are further included. 
     For example, while the PET apparatuses  100  and  200  are respectively shown as an example of the “diagnostic imaging apparatus” according to the present invention in the aforementioned first and second embodiments, and the X-ray imaging apparatus  300  is shown as an example of the “diagnostic imaging apparatus” according to the present invention in the aforementioned third embodiment, the present invention is not restricted to this. The structure according to the present invention may alternatively be applied to an X-ray CT (Computed Tomography) apparatus, an optical CT apparatus, an ultrasonic CT apparatus, an MRI (Magnetic Resonance Imaging) apparatus, etc. used for image diagnosis as the diagnostic imaging apparatus according to the present invention. 
     While the imaging units  1  and  101  are switched to the head imaging state and the breast imaging state so as to respectively image the head T 1  (first target area to be imaged) and the breast T 2  (second target area to be imaged) of the human body T in the aforementioned first and second embodiments, and the imaging unit  201  is switched to the chest imaging state and the breast imaging state so as to respectively image the chest T 3  (first target area to be imaged) and the breast T 2  (second target area to be imaged) of the human body T in the aforementioned third embodiment, the present invention is not restricted to this. According to the present invention, a target area to be imaged of the human body other than the head, the breast, and the chest may be able to be imaged as long as different target areas to be imaged of the human body can be imaged. Furthermore, the target to be imaged is not restricted to the human body. For example, the body of an animal other than a human being may alternatively be a target to be imaged. 
     While the headrest  22  and the head supports  10   b  and  110   b  are provided in the PET apparatuses (diagnostic imaging apparatuses)  100  and  200  in the aforementioned first and second embodiments, the present invention is not restricted to this. According to the present invention, the headrest or the head support may not be provided in the diagnostic imaging apparatus. 
     While the imaging unit  1  ( 101 ,  201 ) is rotated about the rotary shaft  30  ( 130 ,  230 ) by about 90 degrees to be switched to the first state and the second state in each of the aforementioned first to third embodiments, the present invention is not restricted to this. According to the present invention, the rotation angle may alternatively be an angle other than about 90 degrees. For example, in the third embodiment, when the breast is imaged in a tilted state, the imaging unit may be rotated by a rotation angle of less than about 90 degrees to be switched to the first state (chest imaging state) and the second state (breast imaging state). 
     Furthermore, the inner diameters or the shapes of the imaging regions  10   a  and  210   a  may alternatively change according to the target area to be imaged in the aforementioned first to third embodiments. For example, in the first and second embodiments, in the diagnostic imaging apparatus (PET apparatus  100  ( 200 )), the width of the imaging region  10   a  in the upward-downward direction in the imaging unit  1  ( 101 ) may be increased in the head imaging state, and the width of the imaging region  10   a  in the horizontal direction in the imaging unit  1  ( 101 ) may be decreased in the breast imaging state. The diagnostic imaging apparatus is configured as described above such that it is possible to image the target area to be imaged (head or breast) more easily and in more detail. 
     While the rotary shafts  30  and  130  are provided at substantially the same height as that of the upper surface  20   a  of the bed  2  in the aforementioned first and second embodiments, the present invention is not restricted to this. According to the present invention, the position of the rotary shaft is not particularly restricted as long as the imaging unit is rotatable.