JP2010184036A - Radiographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic device capable of acquiring tomographic images of excellent visibility by freely changing the rotation mode of a C-shaped arm 7 to achieve the magnification change of a subject M projected on an FPD (flat panel detector) 4. <P>SOLUTION: The radiographic device has the C-shaped arm 7 and a post 8 supporting the C-shaped arm 7 through a pivot Q. When the C-shaped arm 7 is rotated, the pivot Q moves. The C-shaped arm 7 is rotated around the pivot Q, but since the pivot Q also moves, a distance between an interest portion of the subject M and an X-ray tube 3 is not limited to one distance, that is, the radiographic device is capable of adjusting the distance between the subject M and the X-ray tube 3 according to the purpose of examination. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation imaging apparatus that obtains a radiation projection image of a subject by irradiating radiation, and particularly relates to a radiation imaging apparatus in which a radiation source and a radiation detector are supported by a C-arm.

  There are various configurations of radiation imaging apparatuses that irradiate a subject with radiation and image transmitted radiation that has passed through the subject. For example, there is a configuration in which a radiation source for irradiating radiation and a radiation detector for detecting radiation are supported on both ends of a C-type support member (C-type arm). Such a radiation detector having a C-shaped arm is capable of observing blood vessels arranged three-dimensionally in the body from various angles, for example, angiography of a subject. Used for inspection.

  First, the configuration of the conventional radiation imaging apparatus 51 will be described. As shown in FIG. 8, the conventional radiographic apparatus 51 includes a top plate 52 on which the subject M is placed, an X-ray tube 53 that irradiates the subject M with radiation, a radiation, and a detection element. Two-dimensionally arranged detectors 54, an X-ray tube control unit 56 for controlling the tube power of the X-ray tube 53, a C-type arm 57 for supporting the X-ray tube 53 and the detector 54, and A C-arm drive mechanism 59 for driving and a C-arm drive controller 60 for controlling the C-arm drive mechanism 59 are provided. In addition, the radiation imaging apparatus 51 includes an operation console 61 that receives various instructions from an operator, a display unit 62 that displays a radiation projection image, and a C-type arm operation that collectively executes various controls in the radiation imaging apparatus 51. And a control unit 63. The C-shaped arm 57 is supported by a support column 58.

  Further, in the conventional radiation imaging apparatus 51, tomographic imaging of the subject M can be performed by selecting an imaging mode (see, for example, Patent Document 1). In angiography, the C-arm 57 is stationary during normal fluoroscopic imaging, and captures a radiation projection image of a region of interest of the subject M from a certain direction. There is a case where it is desired to perform tomography of M. This is because it is useful for determining the effects after endovascular treatment, confirming the presence or absence of bleeding, and identifying nutritional blood vessels when performing chemotherapy for tumors. As an advantage that tomography can be performed by the radiation imaging apparatus 51, angiographic examination and tomography can be performed by the same apparatus. By adopting such a configuration, tomography using a radiation tomography apparatus different from the radiation imaging apparatus 51 can be omitted, and the efficiency of examination and the burden on the subject M can be reduced.

  A method of tomography by the conventional radiation imaging apparatus 51 will be described. In order to perform tomography with the conventional radiation imaging apparatus 51, the C-arm is rotated about the support shaft C on which the support 58 supports the C-arm 57. In FIG. 9A, the C-arm 57 is rotated with the body axis direction A of the subject M as the rotation axis. At this time, the X-ray tube 53 and the detector 54 move along the same virtual circle V as shown in FIG. This mode of movement will be referred to as a conventional movement method. In the conventional movement mode, the distance from the site of interest of the subject to the X-ray tube 53 and the distance from the site of interest of the subject to the FPD 4 are the same. The C-shaped arm 57 is rotated while maintaining such a relationship, and the radiation projection images are continuously shot. A series of radiation projection images is converted into a tomographic image of the subject. In addition, this rotating shaft passes the above-mentioned support shaft C. At this time, the distance between the X-ray tube 53 and the site of interest of the subject M is constant regardless of the rotation of the C-arm 57.

JP 2001-104295 A

However, the conventional example having such a configuration has the following problems.
That is, according to the conventional configuration, even if a series of radiation projection images are taken and a tomographic image is acquired, the magnification of the tomographic image cannot be freely changed. That is, the above-described support shaft C is stationary while the C-shaped arm 57 is rotating. Specifically, as shown in FIG. 9, the conventional C-arm 57 is only rotated about a predetermined axis along the body axis A of the subject as a central axis.

  That is, since the distance between the subject M and the X-ray tube 53 cannot be selected during the rotation of the arm 57, the magnification of the image of the region of interest reflected in the acquired radiation projection image depends on the purpose of the examination. Cannot be changed. Therefore, the size of the image of the region of interest reflected in the tomographic image synthesized from these is also constant. If the region of interest of the subject M is small, the only way to obtain a tomographic image suitable for diagnosis is to cut off the end of the tomographic image obtained from a series of radiation projection images and stretch it to form an enlarged image. Absent. Since the detector 54 normally outputs a digital image, the image processing as described above reduces the number of detection elements constituting the enlarged image, and the visibility of the enlarged image is lowered.

  On the other hand, when the region of interest of the subject M is large, the region of interest of the subject M protrudes from the field of view of the tomographic image. Given that the size of the image of the region of interest reflected in the tomographic image is always constant, in order to obtain the entire image of the region of interest, a plurality of tomographic images are acquired once, and these are joined together to obtain the subject M. There is no choice but to acquire a tomographic image of the region of interest. That is, since it is necessary to take tomographic images of the subject M a plurality of times, the time required for tomographic imaging increases. This not only increases the burden on the subject M, but also causes a problem that the tomographic image is disturbed by the body movement of the subject M.

  The present invention has been made in view of such circumstances, and an object of the present invention is to change the magnification of the subject reflected in the detector by freely changing the mode of rotation of the C-arm. Is to provide a radiation imaging apparatus capable of acquiring a tomographic image with excellent visibility.

In order to achieve such an object, the present invention has the following configuration.
Specifically, the radiation imaging apparatus according to claim 1 supports a radiation source that irradiates a radiation beam, a radiation detection unit that detects a radiation beam and outputs a series of radiation projection images, a radiation source, and a radiation detection unit. A support member that supports the support member via a support shaft, a support member rotation control means that controls the relative rotational movement of the support member with respect to the support shaft, and a series of radiation projections. A radiographic apparatus having a reconstruction unit that reconstructs an image and obtains a tomographic image, further comprising a column rotation control unit that controls the rotation of the column, and the support shaft supports the column according to the rotation of the support member. According to the control of the rotation control means, the support member is rotated and moved along the first virtual circle with a predetermined axis parallel to the support shaft as the rotation center axis, and the support member is controlled by the support member rotation control means. The radiation source is rotated in accordance with the rotational movement of the shaft. At that time, the radiation source moves along the second virtual circle with the predetermined axis as the rotation center axis while changing the position in the vertical direction according to the rotational movement of the support member. The radiation detection unit irradiates the radiation beam while being rotated and the third detection unit moves the position in the vertical direction in accordance with the rotational movement of the support member and uses a predetermined axis as the rotation center axis. A series of radiation projection images is taken while being rotated and moved along a virtual circle.

  [Operation / Effect] According to the configuration of the present invention, the support member can be rotated not only with the predetermined axis along the body axis direction of the subject as the central axis but also with a more complicated trajectory. it can. The radiation imaging apparatus according to the present invention includes a support member that supports the radiation detection means and a support column that supports the support member via a support shaft, and the support member is rotated relative to the support column. At this time, the support column is moved according to the control of the support column rotation control means, and the support shaft moves. Although the support member is rotationally moved relative to the support column, according to the present invention, since the support member is also moved, the mode of rotation of the support member becomes more complicated. . Therefore, according to the present invention, the distance between the region of interest of the subject and the radiation source is not limited to one, and the distance between the subject and the radiation source can be adjusted according to the purpose of the examination. When the distance between the subject and the radiation source is increased, the distance between the subject and the radiation detection means is reduced, and the subject is greatly reflected in the radiation detection means. In this way, a tomographic image in which the subject is greatly reflected can be provided.

  Further, according to the above-described configuration, the support shaft is rotated once along the first virtual circle around the predetermined axis. When the support member is rotated once with the support shaft as the rotation center axis, the radiation source is rotated along the second virtual circle with the predetermined axis as the rotation center axis, and the radiation detection means is , And is rotated and moved along a third virtual circle with a predetermined axis as a rotation center axis. With this configuration, the radiation source goes around the subject while maintaining a constant distance from the predetermined axis. The magnification of the subject image reflected on the radiation detection means is determined by the distance between the radiation source and the subject. The predetermined axis of the above configuration can be a position included in the region of interest of the subject. Therefore, the magnification of the image of the region of interest reflected in the radiation detection means is always constant regardless of the rotational movement of the radiation source. That is, the image of the subject is reflected at the same magnification in the series of radiation projection images that are the basis of the tomographic image. Therefore, according to the above configuration, it is possible to provide a radiation imaging apparatus in which the tomographic image can be easily reconstructed by the reconstruction means.

  The radiation detection means and the radiation source are rotated and moved while their positions are varied in the vertical direction. Thereby, tomography can be performed on the subject who is supine.

  According to a second aspect of the present invention, in the radiographic apparatus according to the first aspect, the column rotation control unit includes a first control unit that controls movement of the column in the vertical direction, and movement of the column in the second direction. And a second control means for controlling.

  [Operation / Effect] The above-described configuration represents a specific configuration of the column rotation control means. That is, the column rotation control means is realized by the cooperation of two control means for controlling movements in two directions independent of each other. Therefore, the column rotation control means can move the column not only in rotation but also in various directions.

  According to a third aspect of the present invention, in the radiographic apparatus according to the first or second aspect, the distance between the support shaft and the predetermined shaft can be changed, and the rotational movement direction of the support shaft is also changed. It can be changed.

  [Operation / Effect] According to the above-described configuration, the magnification of the subject image reflected in the radiation projection image can be freely selected. This is because by changing the distance between the radiation source and the predetermined axis, the magnification of the image of the subject reflected in the radiation detection means can be adjusted. Therefore, according to the above configuration, the magnification of the image of the subject reflected in the tomographic image can be changed according to the purpose of the examination.

  The invention according to claim 4 is the radiation imaging apparatus according to any one of claims 1 to 3, wherein the radius of the third virtual circle is smaller than the radius of the second virtual circle. Is.

  [Operation / Effect] According to the above configuration, a series of radiation images are taken with the radiation detection means closer to the subject. The radius of the third virtual circle represents the distance from the site of interest of the subject to the radiation detection means, and the radius of the second virtual circle represents the distance from the site of interest of the subject to the radiation source. The fact that the radius of the third virtual circle is smaller than the radius of the second virtual circle means that the radiation detection means is closer to the subject as compared with the conventional movement method as shown in FIG. 9B. It has become. If a radiation tomographic image is taken in such a state, a radiation tomographic image in which the subject is greatly reflected in the field of view can be acquired.

  According to the configuration of the present invention, the support member can be rotated not only with the predetermined axis along the body axis direction of the subject as the central axis but also with a more complicated trajectory. The support member rotates the support shaft about the rotation center axis. However, according to the present invention, the support shaft also moves, so that the mode of rotation of the support member becomes more complicated. More specifically, the support shaft is rotated once along a first virtual circle centered on the rotation center. In accordance with this, when the support member is rotated once with the support shaft as the rotation center axis, the radiation source is rotated along the second virtual circle around the rotation center, and the radiation detection means is centered on the rotation center. Is rotated along the third virtual circle.

  With such a configuration, the radiation source goes around the subject while keeping the distance from the rotation center constant. Thus, the image of the subject is reflected at the same magnification in the series of radiation projection images that are the basis of the tomographic image.

  In addition, the configuration of the present invention can freely select the magnification of the subject image reflected in the radiation projection image. This is because by changing the distance between the radiation source and the center of rotation, the magnification of the image of the subject reflected in the radiation detection means can be adjusted. Therefore, according to the present invention, the distance between the subject and the radiation source is not limited to one, and the radiation imaging apparatus can adjust the distance between the subject and the radiation detection means in accordance with the purpose of the examination. Can be provided.

1 is a functional block diagram illustrating a configuration of a radiation imaging apparatus according to Embodiment 1. FIG. 3 is a flowchart for explaining the operation of the X-ray imaging apparatus according to Embodiment 1; It is a top view explaining the support | pillar movement step which concerns on Example 1. FIG. 6 is a plan view illustrating an irradiation step according to Example 1. FIG. 6 is a plan view illustrating an irradiation step according to Example 1. FIG. 6 is a plan view illustrating an irradiation step according to Example 1. FIG. 6 is a plan view illustrating an irradiation step according to Example 1. FIG. It is a functional block diagram explaining the structure of the radiography apparatus which concerns on the conventional structure. It is a top view explaining the structure of the radiography apparatus which concerns on the conventional structure.

  Embodiments of the radiation imaging apparatus according to the present invention will be described below with reference to the drawings. In the first embodiment, an X-ray imaging apparatus using X-rays will be described.

  First, the configuration of the X-ray imaging apparatus according to the first embodiment will be described. FIG. 1 is a functional block diagram illustrating the configuration of the radiation imaging apparatus according to the first embodiment. As shown in FIG. 1, the X-ray imaging apparatus 1 according to the first embodiment includes a top plate 2 on which a subject M is placed and an X-ray tube that irradiates an X-ray beam provided below the top plate 2. 3 and a flat panel detector (FPD) 4 that is provided below the top plate 2 and detects X-rays transmitted through the subject M. The X-ray imaging apparatus 1 according to the first embodiment includes an X-ray tube control unit 6 that controls the tube voltage, tube current, and X-ray beam pulse width of the X-ray tube 3. Note that each of the X-ray tube and the FPD corresponds to each of a radiation source and radiation detection means.

  The X-ray tube 3 and the FPD 4 are collectively supported by a C-type arm 7. This arc-shaped C-shaped arm has two tips, and is provided with an X-ray tube 3 at one end and an FPD 4 at the other end. The C-arm 7 is configured to be curved so as to avoid the top plate 2 so as not to interfere with the top plate 2. And this C-type arm 7 becomes a structure supported by the support | pillar 8 arrange | positioned on the floor surface of an examination room. A support shaft Q along the body axis direction A of the subject M is set in the support column 8, and the C-arm 7 rotates relative to the support column 8 with the support shaft Q as a rotation center axis. Moving. The C-shaped arm corresponds to the support member of the present invention.

  The C-type arm 7 can be changed in position and posture. The change of the position of the C-arm 7 is realized by moving the support column 8 horizontally and moving up and down. That is, the X-ray imaging apparatus 1 is provided with a horizontal movement mechanism 9 so that the support column 8 can move horizontally with respect to the floor surface of the examination room. Specifically, the support column 8 can advance and retract along the body axis direction A of the subject M, and can advance and retract along the body side direction S of the subject M. The C-arm 7 can move forward and backward in the body axis direction A and body side direction S of the subject M following the horizontal movement of the support column 8.

  Further, the support column 8 is extendable in the vertical direction, and the X-ray imaging apparatus 1 includes an up-and-down moving mechanism 13 that drives the support column 8 in the vertical direction. Thereby, the relative position in the vertical direction between the subject M and the C-type arm 7 can be changed. The horizontal movement mechanism 9 and the elevation movement mechanism 13 cooperate to rotate the support column 8. The column rotation control unit 10 controls the horizontal movement mechanism 9 and the lifting / lowering movement mechanism 13 collectively to realize rotation of the column 8.

  The column rotation control unit 10 includes a horizontal movement control unit 10 a that controls the horizontal movement mechanism 9 and a vertical movement control unit 10 b that controls the vertical movement mechanism 13. The up / down movement control unit corresponds to the first control means of the present invention, and the horizontal movement control unit corresponds to the second control means of the present invention.

  The C-arm 7 can be changed in posture. That is, the X-ray imaging apparatus 1 is provided with a C-arm rotational movement mechanism 11 and a C-arm rotational movement control unit 12 that controls the C-arm rotational movement mechanism 11. The support shaft Q that is parallel to the direction A is a rotation center axis, and is rotatable and movable relative to the support column 8. In FIG. 1, as indicated by an arrow F, if the C-shaped arm 7 can be rotated relative to the support column 8 in the clockwise direction, the C-type arm 7 can be rotated in the counterclockwise direction. You can also. The C-arm rotational movement control unit corresponds to the support member rotation control means of the present invention.

  Further, the C-arm rotation moving mechanism 11 can also rotate and move the C-arm 7 relative to the support column 8 around the center of curvature of the C-arm 7. That is, by changing the distance between the support shaft Q on which the column 8 supports the C-type arm 7 and the X-ray tube 3, the C-type arm 7 is relatively rotated in the direction indicated by the arrow B in FIG. be able to. As indicated by the arrow B, if the X-ray tube 3 can be relatively rotated in a direction away from the support shaft Q, the X-ray tube 3 is relatively rotated in a direction approaching the support shaft Q. You can also

  As described above, the C-arm 7 can move horizontally in the body axis direction A of the subject M and the body side direction S of the subject M that are orthogonal to each other. The C-arm 7 can be rotated and moved relative to the support column 8 with the body axis direction A of the subject M as the central axis, and the curvature of the C-arm 7 is independent of the direction of the rotation and the direction. A relative rotational movement with respect to the column 8 around the center is also possible. The C-arm 7 can move in the vertical direction by extending and contracting the support column 8. As described above, the X-ray imaging apparatus according to the first embodiment is configured such that the position / posture of the C-arm 7 can be freely changed according to the region of interest of the subject M.

  The X-ray imaging apparatus 1 also includes an image processing unit 15 that converts a detection signal output from the FPD 4 into an X-ray projection image or a moving image, and a reconstruction unit 16 that forms a tomographic image based on a series of X-ray projection images. And an operation console 22 for acquiring the operation of the operator. The operator can change the position / posture of the C-arm 7 through the console 22. The reconstruction unit corresponds to the reconstruction unit of the present invention.

  The X-ray imaging apparatus 1 also includes a C-arm operation control unit 24 that controls the control units 6, 10, and 12 in an integrated manner. The C-arm operation control unit 24 is constituted by a CPU, and realizes the control units 6, 10, and 12 by executing various programs. Each of the above-described controls may be executed by being divided into control devices in charge of them. In addition, the X-ray imaging apparatus 1 according to the first embodiment includes a display unit 23 that displays an X-ray projection image of the subject M. Furthermore, the X-ray imaging apparatus 1 includes a rotation condition data storage unit 20, which will be described later in detail.

Next, an operation when performing an inspection with the X-ray imaging apparatus 1 according to the first embodiment will be described. FIG. 2 is a flowchart for explaining the operation of the X-ray imaging apparatus according to the first embodiment. As shown in FIG. 2, in the examination related to the X-ray imaging apparatus 1 according to the first embodiment, the subject placement step S1 for placing the subject M on the top 2 and the tomography of the subject M are performed. A designation step S2 for inputting the designation, and a posture changing step S3 for changing the posture of the C-arm 7 by rotating the C-arm 7;
By moving the column 8, the column moving step S 4 for adjusting the magnification of the region of interest of the subject M reflected in the FPD 4, the C-arm 7 is rotated, and the column 8 is moved while moving the column 8. An irradiation step S5 for irradiating M, an X-ray projection image acquisition step S6 for acquiring an X-ray projection image, and a tomographic image formation step S7 for forming a tomographic image of the subject M based on a series of X-ray projection images I have. Hereinafter, the details of each step will be described in order.

<Subject placement step S1, and designation step S2>
First, the subject M is laid on the top 2. At this time, the operator can select whether to perform X-ray fluoroscopic imaging or tomographic imaging by operating the console 22. This X-ray fluoroscopic imaging is a mode in which the C-arm 7 and the support column 8 are once moved, and thereafter spot imaging is performed without changing the position / posture. In the tomography, the positions and postures of the C-type arm 7 and the support column 8 are once set to the initial state described later, and then the X-ray projection images are continuously shot while the C-type arm 7 is rotated. It is a form of acquiring an image. In the description of the first embodiment, it is assumed that the operator designates tomography in the designation step S2.

<Attitude change step S3>
To perform tomography, first, the C-arm 7 is rotated so as to be suitable for tomography. Specifically, the C-type arm 7 is rotated around the center of curvature of the C-type arm 7 so that the X-ray tube 3 and the FPD 4 are in the same position in the body axis direction A. As will be described later, when X-ray projection images are continuously shot for the purpose of obtaining a tomographic image, the C-arm 7 is rotated in the body axis direction A of the subject M. At this time, when forming a tomographic image, it is desirable that the X-ray tube 3 and the FPD 4 are in the same position in the body axis direction A as shown in FIG. If the X-ray tube 3 and the FPD 4 are not in the same position in the body axis direction A, the shadow of the subject M reflected on the FPD 4 is shifted along the body axis direction A according to the rotation of the C-type arm 7. This is because the calculation for forming the tomographic image becomes complicated.

<Staff moving step S4>
Then, the operator moves the support column 8 in the vertical direction through the console 22. Then, following this, the C-arm 7 also moves up and down. By this operation, as shown in FIG. 3, the distance between the region of interest of the subject M and the X-ray tube 3 is set. As shown in FIG. 3A, when the distance between the region of interest of the subject M and the X-ray tube 3 is increased by moving the C-arm 7 vertically downward, a cone-shaped X-ray beam is obtained. Since the distance between the X-ray tube 3 that irradiates and the subject M becomes longer, the image of the region of interest of the subject M reflected in the FPD 4 is reduced. This is because the width of the cone-shaped X-ray beam passing through the subject M is wider, and the cone-shaped X-ray beam passes through a wide range of the subject M.

  Moreover, in this support | pillar movement step S4, turning radius DC which is the distance of the spindle Q of the support | pillar 8 mentioned later and the predetermined axis | shaft R is determined. That is, in the configuration of the first embodiment, when the support column 8 is moved in the vertical direction, the turning radius DC is calculated. This rotational radius DC is the radius of rotational movement of the support shaft Q of the support column 8.

  The predetermined axis R will be described. The predetermined axis R is a fixed axis that is spaced vertically upward from the top plate 2. When the support column 8 is moved in the vertical direction, the support shaft Q also moves following this, so that the distance between the predetermined shaft R and the support shaft Q can be changed. The X-ray imaging apparatus 1 according to the first embodiment reads the distance between the predetermined axis R and the support shaft Q according to the vertical movement of the support column 8 and sets this as the rotation radius DC. The rotation radius DC is stored in the rotation condition data storage unit 20. This predetermined axis R is the center of the rotational movement of the support shaft Q of the support column 8.

  On the other hand, as shown in FIG. 3B, when the distance between the region of interest of the subject M and the X-ray tube 3 is shortened by moving the C-arm 7 vertically upward, a cone-shaped X-ray beam is obtained. Since the distance between the X-ray tube 3 that irradiates and the subject M is shortened, the image of the region of interest of the subject M reflected in the FPD 4 is enlarged. This is because the width of the cone-shaped X-ray beam passing through the subject M is narrower, and the cone-shaped X-ray beam passes through a limited range of the subject M. Thus, in the support column moving step S4, the size of the region of interest of the subject M reflected in the FPD 4 can be adjusted. That is, according to the configuration of the first embodiment, the magnification of the region of interest of the subject M reflected in the FPD 4 can be adjusted. A point belonging to the region of interest of the subject M after the column moving step S4 is finished is defined as a predetermined axis R, a separation distance between the predetermined axis R and the X-ray tube 3 is defined as D3, and the predetermined axis R and the FPD 4 are separated from each other. The separation distance is D4 (see FIG. 4). The magnification of the region of interest of the subject M in the FPD 4 is determined by these D3 and D4. Note that when D4 is smaller than D3, the region of interest of the subject is greatly reflected in the FPD 4, and a tomographic image in which the region of interest is largely reflected in the imaging field of view can be provided.

  In the support column moving step S4, the rotational movement direction of the support shaft Q of the support column 8 is uniquely derived together with the rotation radius DC and stored in the rotation condition data storage unit 20. The direction of this rotational movement will be described later, including its derivation method. As described above, in the radiation imaging apparatus according to the first embodiment, the distance between the support shaft Q and the predetermined axis R can be changed, and the rotational movement direction of the support shaft Q can also be changed. .

<Irradiation step S5>
When the operator instructs X-ray exposure through the console 22, when viewed from the body axis direction A of the subject M, the X-ray tube 3 and the FPD 4 have the predetermined axis R as the rotation center axis and the subject. It rotates along a virtual circle orthogonal to the body axis direction A of the specimen M. That is, as shown in FIG. 4, the X-ray tube 3 and the FPD 4 rotate in the direction of the arrow. The X-ray tube 3 is intermittently irradiated with a cone-shaped X-ray beam while being rotated, and the FPD 4 detects the X-ray beam while being rotated, and X-ray tube X is detected based on the detection signal each time. A line projection image is formed.

  In the present invention, the most characteristic X-ray tube 3 and the mode of rotation of the FPD 4 will be described. That is, as shown in FIG. 4, the FPD 4 makes a round around the subject M along a virtual circle V4 having a radius of D4. Similarly, the X-ray tube 3 (more precisely, the focal point of the X-ray beam) goes around the subject M along a virtual circle V3 having a radius of D3. In the irradiation step S5, D3 and D4 are maintained even while the X-ray tube 3 and the FPD 4 are rotating. Therefore, the magnification of the region of interest of the subject M in the FPD 4 is also maintained during the execution of the irradiation step S5. Will be. Note that the virtual circle V3 and the virtual circle V4 correspond to the second virtual circle and the third virtual circle of the present invention, respectively.

  Attention is paid to the movement of the C-arm 7 at this time. As shown in FIG. 5, when the C-arm 7 is viewed from the body axis direction A of the subject M, the C-arm 7 is linear, which is just a line connecting the X-ray tube 3 and the FPD 4. Matches the minute. The predetermined axis R is parallel to the body axis direction A of the subject M and the support shaft Q. When the X-ray tube 3 and the FPD 4 are rotated, all points belonging to the C-arm 7 follow a circular trajectory having a predetermined axis R as the rotation center axis and orthogonal to the body axis direction A of the subject M. Draw. That is, the support shaft Q of the support column 8 makes one rotation along the virtual circle VC. The radius of the virtual circle VC is the turning radius DC, which is the distance between the predetermined axis R and the support shaft Q of the column 8. The rotation radius DC is included in the condition data read from the rotation condition data storage unit 20, and the column rotation control unit 10 collectively controls the movement of the column 8 based on the condition data. The virtual circle VC corresponds to the first virtual circle of the present invention. The turning radius DC corresponds to the distance between the support shaft of the present invention and a predetermined axis. The C-arm rotational movement control unit 12 rotates and moves the C-arm 7 in accordance with the rotation of the support column 8. Then, the X-ray tube 3 and the FPD 4 move along the virtual circle V3 and the virtual circle V4 while changing the position in the vertical direction.

  In the first embodiment, the magnification of the region of interest of the subject M reflected in the FPD 4 is adjusted by adjusting the rotation radius DC and the direction of the rotational movement of the support shaft Q in the support column 8. That is, when DC is 0, D3 and D4 are equal. When the support shaft Q of the support column 8 is rotated in a predetermined direction and DC is gradually increased, D3 gradually decreases, and the image of the region of interest of the subject M reflected in the FPD 4 is enlarged. The In addition, when the support shaft Q of the support column 8 is rotated in the direction opposite to the predetermined direction, and DC is gradually increased, D3 gradually increases and an image of the region of interest of the subject M reflected in the FPD 4 is obtained. Is reduced. That is, in the X-ray imaging apparatus 1 according to the first embodiment, the C-arm is moved in the body axis direction while moving the support shaft Q of the support column 8 according to the DC stored in the rotation condition data storage unit 20 and the direction of the rotational movement. It is configured to rotate while being inclined to A.

  That is, the support shaft Q of the support column 8 is rotationally moved along the virtual circle VC with the predetermined axis R as the rotation center axis. In synchronization with this, the X-ray tube 3 is rotationally moved along an imaginary circle V3 having a predetermined axis R as a rotation center axis. In synchronization with these, the FPD 4 is rotationally moved along a virtual circle V4 with the predetermined axis R as the rotation center axis. When the support shaft Q of the support column 8 makes one rotation, the X-ray tube 3 and the FPD 4 also make one rotation in accordance with this. Moreover, the support shaft Q is parallel to the body axis direction A of the subject M, and the virtual circle V3, the virtual circle V4, and the virtual circle VC are all orthogonal to the predetermined axis R.

  Further, the direction of rotational movement of the support shaft Q in the support column 8 in the irradiation step S5 is determined in advance in the above-described support column moving step S4. That is, when the predetermined axis R is vertically above the support shaft Q as shown in FIG. 3A, and when the predetermined axis R is vertically below the support shaft Q as shown in FIG. The direction of rotational movement of the support shaft Q is appropriately selected. Specifically, in the case of FIG. 3A, the support shaft Q is rotated in the same direction as the X-ray tube 3 as shown in FIG. 6. 3B, the support shaft Q is rotated in the same direction as the FPD 4 as shown in FIG.

<X-ray projection image acquisition step S6 and tomographic image formation step S7>
The detection signal acquired in the irradiation step S5 is sent to the image processing unit 15, where it is converted into an X-ray projection image. The series of X-ray projection images obtained here are obtained by capturing the region of interest of the subject M while changing the imaging direction, and are sent to the reconstruction unit 16 and converted into a tomographic image. This tomographic image is displayed on the display unit 23. With this, the acquisition of the tomographic image by the radiation imaging apparatus according to the first embodiment is completed.

  As described above, according to the configuration of the first embodiment, the C-arm 7 is not only rotated about the predetermined axis along the body axis direction A of the subject M as a central axis, but also has a more complicated locus. Can be rotated. The X-ray imaging apparatus 1 according to the configuration of the first embodiment includes a C-type arm 7 that supports the FPD 4 and a support column 8 that supports the C-type arm 7 via a support shaft Q. The C-type arm 7 rotates. At that time, the support column 8 is moved according to the control of the support column rotation control unit 10, and the support shaft Q moves accordingly. The C-type arm 7 rotates relative to the support column 8 around the support shaft Q. According to the configuration of the first embodiment, the support column 8 and the C-type arm 7 are rotated in accordance with the rotation of the C-type arm 7. Since the support shaft Q also moves, the manner of rotation of the C-arm 7 becomes more complicated. Therefore, according to the configuration of the first embodiment, the distance between the subject M and the X-ray tube 3 is not limited to one, and the distance between the subject M and the X-ray tube 3 is set according to the purpose of the examination. An X-ray imaging apparatus 1 that can be adjusted can be provided.

  Further, according to the configuration of the first embodiment, in the irradiation step S5, the support shaft Q is rotated once along the virtual circle VC with the predetermined axis R as the rotation center axis. In synchronism with this, when the C-arm 7 is rotated once around the support shaft Q, the X-ray tube 3 is rotationally moved along a virtual circle V3 having a predetermined axis R as the rotation center axis, and the FPD 4 is Then, it is rotated and moved along a virtual circle V4 with the predetermined axis R as the rotation center axis. With such a configuration, the X-ray tube 3 goes around the subject M while keeping the distance from the predetermined axis R constant. The magnification of the image of the subject M reflected in the FPD 4 is determined by the distance D3 between the X-ray tube 3 and the predetermined axis R. Therefore, the magnification of the image of the subject M reflected in the FPD 4 is always constant regardless of the rotational movement of the X-ray tube 3. That is, the image of the subject M is reflected at the same magnification in the series of X-ray projection images that are the basis of the tomographic image. Therefore, according to the configuration of the first embodiment, the X-ray imaging apparatus 1 in which the reconstruction unit 16 can easily reconstruct a tomographic image can be provided.

  Moreover, according to the structure of Example 1, in the support | pillar moving step S4, the magnification of the image of the subject M reflected in the X-ray projection image can be freely selected. This is because the magnification of the image of the subject M reflected in the FPD 4 can be adjusted by changing the distance between the X-ray tube 3 and the predetermined axis R. Therefore, according to the configuration of the first embodiment, the magnification of the image of the region of interest of the subject M that is reflected in the tomographic image can be changed according to the purpose of the examination. As described above, the distance between the X-ray tube 3 once set and the predetermined axis R is maintained in the irradiation step S5.

  Further, according to the configuration of the first embodiment, a series of X-ray images are taken with the FPD 4 closer to the subject. The radius of the virtual circle V4 represents the distance from the site of interest of the subject M to the FPD 4, and the radius of the virtual circle V3 represents the distance from the site of interest of the subject M to the X-ray tube 3. Since the radius of the virtual circle V4 is smaller than the radius of the virtual circle V3, the FPD 4 is closer to the subject M than the conventional movement method as shown in FIG. ing. If an X-ray tomographic image is taken in such a state, an X-ray tomographic image in which the subject is greatly reflected in the field of view can be acquired.

  The present invention is not limited to the configuration of the above embodiment, and can be modified as follows.

  (1) In the embodiment described above, the support column 8 that supports the C-arm 7 is disposed on the floor surface of the examination room, but the present invention is not limited to this. It is good also as a structure which arrange | positions the support | pillar 8 on the ceiling of a test room and suspends the C-type arm 7 on the support | pillar 8.

  (2) In the above-described embodiments, the FPD has been described as a specific example of the radiation detection means, but the present invention is not limited to this. As the radiation detection means, an image intensifier that converts radiation into visible light and displays it may be used.

  (3) In the embodiment described above, the X-ray imaging apparatus 1 is provided with the single C-type arm 7, but the present invention is not limited to this. The present invention may be applied to a biplane system provided with two C-type arms 7.

1 X-ray equipment (radiography equipment)
3 X-ray tube (radiation source)
4 FPD (radiation detection means)
7 C-type arm (support member)
8 Support column Q Support shaft 10 Support column rotation control part (support column rotation control means)
10a Horizontal movement control unit (second control means)
10b Elevating / lowering control unit (first control means)
12 C-type arm rotation movement control unit (support member rotation control means)
16 Reconfiguration unit (reconfiguration means)
DC turning radius (distance between spindle and specified axis)
V3 virtual circle V3 (second virtual circle)
V4 virtual circle V4 (third virtual circle)
VC Virtual circle VC (first virtual circle)
R Predetermined axis

Claims (4)

A radiation source for irradiating the radiation beam; a radiation detection means for detecting the radiation beam and outputting a series of radiation projection images; a support member for supporting the radiation source and the radiation detection means; and a support shaft. A support column for supporting the support member, a support member rotation control means for controlling the relative rotational movement of the support member with respect to the support column, with the support shaft as a rotation center axis, and a series of the radiation projection images are reconstructed. In a radiographic apparatus equipped with a reconstruction means for acquiring a tomographic image,
It further comprises a column rotation control means for controlling the rotation of the column,
The support shaft is rotated and moved along a first imaginary circle with a predetermined axis parallel to the support shaft as a rotation center axis according to the control of the support column rotation control means in accordance with the rotation of the support member. With
The support member is rotated according to the rotational movement of the support shaft according to the control of the support member rotation control means,
At that time, the radiation source is rotated while moving along a second virtual circle having the predetermined axis as a rotation center axis while changing the position in the vertical direction in accordance with the rotation of the support member. Irradiation
Along with this, the radiation detecting means is rotated and moved along a third imaginary circle having the predetermined axis as the rotation center axis while changing the position in the vertical direction in accordance with the rotational movement of the support member. A radiation imaging apparatus for capturing a series of radiation projection images. The radiographic apparatus according to claim 1,
The column rotation control means includes:
First control means for controlling the vertical movement of the column;
And a second control unit configured to control movement of the column in the second direction. The radiographic apparatus according to claim 1 or 2,
The distance between the support shaft and the predetermined shaft can be changed,
The radiation imaging apparatus characterized in that the direction of the rotational movement of the support shaft can also be changed. The radiographic apparatus according to any one of claims 1 to 3,
The radiation imaging apparatus according to claim 1, wherein a radius of the third virtual circle is smaller than a radius of the second virtual circle.

Images