JP2010184037A - Radiation tomography apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation tomography apparatus for performing easier control in acquiring a tomographic image with a wide visual field range. <P>SOLUTION: The radiation tomography apparatus projects an FPD (Flat Panel Detector) 4 to a C type arm 7 in the progression direction when the FPD 4 starts rotating. When the C type arm 7 is rotated around an isocenter in this state, a visual field area of a tomographic image to be reconstructed is also shifted. In succession to the rotation, the FPD 4 is projected to the C type arm 7 in the opposite direction (the direction opposite to the direction in which the FPD is projected) of the rotation of the FPD 4. When the C type arm 7 is rotated around the isocenter P again, the visual field area of the tomographic image reconstructed is shifted again as the projection direction changes. When an X-ray radiographic image in the visual field range where the positions are shifted from each other is used to reconstruct a single tomographic image, a tomographic image of a subject is acquired in a wide range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation tomography apparatus capable of acquiring a tomographic image of a subject, and in particular, radiation that rotates and moves while maintaining a relative positional relationship between a radiation source that irradiates radiation and a radiation detector that detects the radiation. The present invention relates to a tomography apparatus.

  There are various configurations of radiation tomography 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). A radiation detector having such a C-shaped arm is easy to inject a contrast medium into a subject while photographing a radiation projection image, and is used, for example, for angiographic examination of a subject.

  First, the configuration of the conventional radiation tomography apparatus 51 will be described. As shown in FIG. 11, the conventional radiation tomography apparatus 51 detects a radiation, a top plate 52 on which the subject M is placed, a radiation source 53 that irradiates the subject M with a radiation beam, A radiation detector 54 in which detection elements are two-dimensionally arranged, a radiation source controller 56 that controls the tube power of the radiation source 53, a C-type arm 57 that supports the radiation source 53 and the radiation detector 54, A C-type arm drive mechanism 59 for driving this and a C-type arm drive control unit 60 for controlling the C-type arm drive mechanism 59 are provided. The C-shaped arm 57 is supported by a support column 58. The C-type arm 57 can rotate around the body axis of the subject M, and accordingly, the radiation detector 54 and the radiation source 53 rotate while maintaining their relative positions.

  Such a radiation tomography apparatus 51 can also acquire a tomographic image of the subject M. That is, a tomographic image obtained by acquiring a plurality of radiographic images of the subject while rotating the C-arm 57 around the central axis C and cutting the subject M along a plane perpendicular to the body axis direction based on these images. (Axial image) can be taken. The radiation source 53 and the radiation detector 54 pivot around the same center point P as the C-arm 57 makes one rotation around the center axis C. The center point P is called an isocenter in the sense of the center of rotation of the C-arm 57, and the center axis C passes through the isocenter (center point P).

  In order to acquire a tomographic image of the subject M using the radiation tomography apparatus 51, as shown in FIG. 12, a tomographic image is applied to the visual field region R1 where the radiation beam is always irradiated regardless of the rotation of the C-arm 57. The region of interest to be imaged must be included. Otherwise, it is not possible to collect all the data necessary for the reconstruction of the tomographic image of the subject M. Such a limitation becomes a significant problem when a tomographic image having a large cross-sectional area such as the abdomen of the subject M is to be acquired.

  In order to compensate for the shortage of the visual field range described above, the conventional radiation tomography apparatus employs a method of obtaining a tomographic image of the subject M by rotating the C-arm 57 twice. That is, as shown in FIG. 13, the radiation detector 54 is moved forward in the body side direction of the subject M before acquiring the fluoroscopic image that is the basis of the tomographic image, and the radiation source 53 and the radiation detector 54 are moved. Tilt to face each other. Then, the radiation source 53 and the radiation detector 54 are rotated around a virtual center point V different from the previous center point P. At this time, a plurality of radiographic images are taken. And when the radiation source 53 and the radiation detector 54 make one rotation, it will return to the state of FIG. In this case, the spread angle of the radiation beam is θ.

  From this state, the C-arm 57 shifts to the second rotation. Prior to the rotation, the radiation source 53 and the radiation detector 54 are tilted in the direction opposite to that shown in FIG. 13 (see FIG. 14). Then, the radiation source 53 and the radiation detector 54 are rotated around the previous virtual center point V. At this time, a plurality of radiographic images are taken. And when the radiation source 53 and the radiation detector 54 make one rotation, it will be in the state of FIG. At this time, the spread angle of the radiation beam is also θ.

  According to the conventional configuration, by irradiating a subject with a radiation beam having a divergence angle of θ twice, as shown in FIG. 53 and the radiographic images equivalent to those obtained by rotating the two radiation detectors 54a and 54b once can be acquired. As a result, the field of view of the reconstructed tomographic image is within the circle of R2 centered on the virtual center point V (see FIG. 15), and is wider than the field of view range R1 in FIG. . Thereby, a tomographic image having a large cross-sectional area can be acquired. A radiation tomography apparatus having such a configuration is described in Patent Document 1, for example.

JP-A-11-253435

However, such a conventional configuration has the following problems.
That is, the conventional configuration of the radiation tomography apparatus is complicated to control. The central axis C does not pass through the virtual center point V. In the imaging method in which the C-arm 57 rotates twice, the radiation source 53 and the radiation detector 54 no longer rotate around the isocenter P, but center on a virtual center point V that is different from the isocenter P. It rotates.

  As shown in FIG. 12, if the radiation source 53 and the radiation detector 54 are rotated around the isocenter P, the C-arm 57 may be simply rotated. However, in the imaging method in which the C-arm 57 rotates twice, as shown in FIG. 16, while the radiation source 53 and the radiation detector 54 make a round around the virtual center point V, the isocenter P also has the virtual center point V. Make a round around. That is, it is necessary to accurately change the position of the isocenter P in the C-type arm 57 in accordance with the inclination angle of the C-type arm 57. For the sake of understanding, only the C-arm 57 is extracted as shown in FIG. From this figure, it can be seen that the C-shaped arm 57 has a complicated motion of moving so as to be tangent to a virtual circle centered on the virtual center point V. The movement of the isocenter P of the C-type arm 57 is performed by the movement of the column 58 that supports the C-type arm 57 (see FIG. 11). The support column 58 expands and contracts in the vertical direction, and moves the isocenter P of the C-arm 57 by moving back and forth in the body side direction of the subject M. That is, according to the conventional configuration, when acquiring a tomographic image with a wide visual field range, the C-type arm 57 must be moved in accordance with the inclination of the C-type arm 57, and the control of the apparatus is complicated. turn into.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation tomography apparatus capable of making control easier when acquiring a tomographic image with a wide visual field range. There is.

The present invention has the following configuration in order to solve such problems.
That is, the invention described in claim 1 is a radiation source that irradiates a radiation beam, a radiation detection means that detects the radiation beam, a support member that supports the radiation source and the radiation detection means, and a predetermined rotation center. In a radiation tomography apparatus including a support member rotation control unit that rotates and moves a radiation source and a radiation detection unit by rotating the support member, and a tomographic image acquisition unit that acquires a tomographic image, the support member and the radiation detection The radiation detection means is moved relative to the support member by moving the radiation detection means forward and backward along the tangential direction of the rotational movement at the time of rotation start. Detector shift means for projecting in either the traveling direction side at the start of rotation or (B) the opposite direction side; and a detector shift A detector shift control means for controlling the means, and the detector shift control means projects the radiation detection means toward one direction of either (A) or (B), and this state is A plurality of fluoroscopic images are acquired while rotating the radiation source and the radiation detection means while maintaining the position, and subsequently, the radiation detection means protrudes in the direction opposite to the one direction by the detector shift control means. A plurality of fluoroscopic images are acquired while rotating the radiation source and the radiation detecting means while maintaining this state, and the tomographic image acquiring means obtains the tomographic images based on the acquired radiographic images. It is characterized by acquiring.

  [Operation and Effect] According to the configuration of the present invention, the detector shift means is provided. The detector shift means moves the radiation detection means forward and backward along the traveling direction side at the time of starting rotation. In the first rotation of the support member, for example, the radiation detection means is projected from the support member in the direction of travel when the rotation of the radiation detection means is started. When the support member is rotated around a predetermined rotation center in this state, the detector shift means rotates accordingly. However, since the radiation detection means is in a state of overhanging the support member, the rotation center of the radiation detection means deviates from the rotation center of the support member. By doing so, the visual field region of the reconstructed tomographic image is also shifted. Then, this time, the radiation detection means is caused to project with respect to the support member in the direction opposite to the rotation of the radiation detection means (the direction opposite to the direction in which the radiation is projected). When the support member is rotated again around a predetermined rotation center in this state, the reconstructed tomographic field of view area is shifted again with the change of the projecting direction. Thus, if a single tomographic image is reconstructed using the radiographic images in the visual field range of the first rotation and the second rotation whose positions are shifted from each other, a tomographic image of the subject can be acquired over a wide range. The visual field range at this time is a new visual field range obtained by superimposing the visual field ranges. As described above, according to the configuration of the present invention, it is possible to acquire radioscopic images in a visual field range in which the positions are shifted from each other only by rotating the support member around the predetermined rotation center. Since it is not necessary to perform a complicated movement such as moving so as to contact the virtual circle, the control of the support member rotation control means becomes simple.

  The invention according to claim 2 is the radiation tomography apparatus according to claim 1, wherein the radiation tomography apparatus is provided at a position where the support member and the radiation source are interposed, and the radiation source is tangent to the rotational movement at the start of rotation of the radiation source. Radiation that causes the radiation source to project in either the traveling direction side (C) at the start of rotation of the radiation source or (D) the opposite direction side relative to the support member by moving forward and backward along the direction. A radiation source shift control means for controlling the radiation source shift means and the radiation source shift means, and when the radiation detection means protrudes to the support member in the direction of travel at the time of rotation start of the radiation detection means (A), The radiation source shifting means causes the radiation source to protrude from the support member in the direction opposite to the traveling direction when the radiation source starts rotating (D) and is supported by the radiation detection means. In the case where (B) the radiation detection means protrudes in the direction opposite to the traveling direction at the time of starting rotation of the radiation detection means, the radiation source shift means is configured so that the radiation source is placed on the support member. It is characterized by projecting in the direction of travel in

  [Operation / Effect] According to the above configuration, the radiation source shifting means is provided. This radiation source shift means moves the radiation source forward and backward along the traveling direction side at the time of starting rotation. When the support member is rotated twice, the radiation source also protrudes from the support means. Specifically, (A) when the radiation detection means protrudes from the support member in the direction of travel at the time of rotation start, the radiation source shift means sets the radiation source to the support member at the time of rotation start. Project to the opposite side of the direction of travel. Similarly, (B) when the radiation detection means protrudes from the support member in the direction opposite to the traveling direction at the start of rotation, the radiation source shift means rotates the radiation source relative to the support member. Project in the direction of travel at the start. When the support member rotates, the radiation source and the radiation detection means rotate so as to follow each other, so that the traveling direction side when the radiation source starts rotating and the traveling direction side when the radiation detection means starts rotating , Of course, they are in opposite directions. That is, in the case of (A), the traveling direction side at the time of starting rotation of the radiation detecting means and the opposite direction side of the traveling direction at the time of starting rotation of the radiation source are in the same direction. Further, in the case of (B), the same applies to the direction opposite to the traveling direction at the time of starting rotation of the radiation detecting means and the direction of traveling at the time of starting rotation of the radiation source. Based on the above, the radiation detection means and the radiation source protrude from the support member in a state in which the positional relationship between them is maintained. Therefore, the radiation applied from the radiation source is surely captured by the radiation detection means.

  According to a third aspect of the present invention, the radiation tomography apparatus according to the first aspect is provided at a position where the support member and the radiation source are interposed, and supports the radiation source by tilting the radiation source. (M) Radiation source tilting means for tilting in the direction of either the traveling direction at the time of starting rotation of the radiation source or (N) the opposite direction side, and the radiation source tilt for controlling the radiation source tilting means Control means, and when the radiation detection means protrudes from the support member (A) in the advancing direction at the start of rotation of the radiation detection means, the radiation inclination means places the radiation source relative to the support member (N ) Inclined to the opposite side of the traveling direction at the start of rotation of the radiation source, and the radiation detecting means is opposite to the support member. If overhanging side, the radiation inclining means is characterized in that the tilting in the traveling direction at the time of start of rotation of the radiation source with respect to the support member (M) radiation source.

  [Operation / Effect] According to the above configuration, the radiation source tilting means is provided. The radiation source tilting unit tilts the radiation source along the traveling direction side at the time of starting rotation. When the support member is rotated twice around a predetermined center of rotation, the radiation source is tilted toward the radiation source tilting means. Specifically, (A) when the radiation detection means protrudes from the support member in the direction of travel at the time of starting rotation, the radiation source tilting means applies the radiation source to the support member at the time of rotation start. Tilt to the opposite side of the direction of travel. Similarly, (B) when the radiation detection means protrudes from the support member in the direction opposite to the traveling direction at the start of rotation, the radiation source tilting means rotates the radiation source relative to the support member. Tilt to the direction of travel at start-up. When the support member rotates, the radiation source and the radiation detection means rotate so as to follow each other, so that the traveling direction side when the radiation source starts rotating and the traveling direction side when the radiation detection means starts rotating , Of course, they are in opposite directions. That is, in the case of (A), the traveling direction side at the time of starting rotation of the radiation detecting means and the opposite direction side of the traveling direction at the time of starting rotation of the radiation source are in the same direction. Further, in the case of (B), the same applies to the direction opposite to the traveling direction at the time of starting rotation of the radiation detecting means and the direction of traveling at the time of starting rotation of the radiation source. Based on the above, the radiation source is directed to the radiation detection means side regardless of which direction the radiation detection means protrudes with respect to the support member. Therefore, the radiation applied from the radiation source is surely captured by the radiation detection means.

  According to the structure of this invention, the detector shift means is provided. The detector shift means causes the radiation detection means to move forward and backward to project from the support means. When the support member is rotated around a predetermined rotation center in this state, the detector shift means rotates accordingly. However, since the radiation detection means is in a state of overhanging the support member, the rotation center of the radiation detection means deviates from the rotation center of the support member. By doing so, the visual field region of the reconstructed tomographic image is also shifted. Subsequently, the radiation detection means is projected to the opposite direction side with respect to the support member. When the support member is rotated again around the predetermined rotation center in this state, the reconstructed tomographic field of view area is shifted again as the projecting direction is changed. If a single tomographic image is reconstructed using radioscopic images in the visual field range where the positions are shifted from each other, a tomographic image of the subject can be acquired over a wide range. As described above, according to the configuration of the present invention, a tomographic image of a subject can be acquired over a wide range only by rotating the support member twice around a predetermined rotation center. There is no need for complex movements such as moving in contact.

1 is a functional block diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 3 is a flowchart for explaining the operation of the radiation tomography apparatus according to Embodiment 1. 1 is a schematic diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 1 is a schematic diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 1 is a schematic diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 1 is a schematic diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. It is sectional drawing explaining the structure of one modification of this invention. It is a functional block diagram explaining the structure of one modification of this invention. It is a functional block diagram explaining the structure of one modification of this invention. It is a schematic diagram explaining the structure of 1 modification of this invention. It is a functional block diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure. It is a schematic diagram explaining the radiation tomography apparatus of a conventional structure.

  Embodiments of a radiation tomography apparatus according to the present invention will be described below with reference to the drawings. In addition, the X-ray in Example 1 is an example of the radiation which concerns on this invention.

  First, the configuration of the X-ray tomography apparatus 1 according to the first embodiment will be described. FIG. 1 is a functional block diagram illustrating the configuration of the radiation tomography apparatus according to the first embodiment. As shown in FIG. 1, the X-ray tomography apparatus 1 according to the first embodiment includes a top plate 2 that can move forward and backward along the body axis direction of the subject M on which the subject M is placed, and a top plate 2. An X-ray tube 3 for irradiating an X-ray beam provided on the lower side and a flat panel detector (FPD) 4 provided on the upper side of the top plate 2 and detecting X-rays transmitted through the subject M are provided. ing. The X-ray tomography apparatus 1 according to the first embodiment has 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. The arcuate C-shaped arm 7 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. The C-shaped arm corresponds to the support member of the present invention.

  Further, the C-arm 7 can change the inclination angle. In other words, the X-ray tomography apparatus 1 is provided with a C-type arm rotational movement mechanism 11 and a C-type arm rotational movement control unit 12 that controls the C-type arm rotational movement mechanism 11. It can rotate and move around a central axis Q parallel to the direction A in which the tip protrudes (parallel to the body axis direction of the subject M). That is, in FIG. 1, as indicated by the arrow F, the column 8 can be rotated clockwise about the fulcrum supporting the C-shaped arm 7 as the center of rotational movement. It can also be rotated. Note that the C-arm rotation 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 the C-arm 7 around the center of curvature of the C-arm 7. That is, by changing the distance between the fulcrum at which the support column 8 supports the C-arm 7 and the X-ray tube 3, the C-arm 7 can be rotated in the direction indicated by the arrow G in FIG. Further, if the X-ray tube 3 can be rotated in a direction away from the fulcrum, conversely, the X-ray tube 3 can also be rotated in a direction approaching the fulcrum.

  The isocenter of the present invention will be described. The isocenter means the center of rotational movement of the C-arm 7. The C-type arm 7 rotates around the center axis Q along the protruding direction A of the tip, and further rotates around the center of curvature of the C-type arm 7 as indicated by an arrow G in FIG. In other words, the C-type arm 7 rotates around the central axis along the width direction S of the C-type arm 7 (through the paper surface in FIG. 1). That is, the C-type arm has two types of rotating shafts. These rotation axes intersect at a certain point. This is the isocenter of the C-arm, which is the center of rotation for both types of rotation.

  The X-ray tomography apparatus 1 includes an image processing unit 15 that converts a signal output from the FPD 4 into an X-ray fluoroscopic image, and a reconstruction unit 16 that reconstructs the X-ray fluoroscopic image and acquires a tomographic image. I have. The reconstruction unit 16 corresponds to a tomographic image acquisition unit of the present invention. In the X-ray tomography apparatus 1, the operator can change the position / posture of the C-arm 7 through the console 22. The reconstruction unit corresponds to a tomographic image acquisition unit of the present invention.

  The X-ray grid 5 is provided so as to cover the X-ray detection surface of the FPD 4. In this X-ray grid 5, an absorbing foil that absorbs scattered X-rays generated inside the subject is arranged. By providing the X-ray grid 5, it is possible to obtain a tomographic image with high contrast. The X-ray tube 3 is provided with a collimator 9 that collimates the X-rays emitted from the X-ray tube 3. X-rays output from the X-ray tube 3 are emitted toward the subject M as a cone-shaped X-ray beam by the collimator 9. The opening degree of the collimator 9 is controlled by the collimator controller 10.

  An X-ray tube shift mechanism 31 is provided at a position between the X-ray tube 3 and the C-arm 7. The X-ray tube shift mechanism 31 is controlled by an X-ray tube shift control unit 32. By providing the X-ray tube shift mechanism 31, the relative positional relationship between the X-ray tube 3 and the C-arm 7 can be changed. Specifically, the X-ray tube 3 can move forward and backward with respect to the C-type arm 7 along the direction A in which the tip of the C-type arm 7 projects, and the width direction S of the C-type arm 7 (of the subject M). It can move forward and backward along the body axis direction.

  Similarly, an FPD shift mechanism 33 is provided at a position between the FPD 4 and the C-arm 7. The FPD shift mechanism 33 is controlled by the FPD shift control unit 34. By providing the FPD shift mechanism 33, the relative positional relationship between the FPD 4 and the C-type arm 7 can be changed. Specifically, the FPD 4 can move forward and backward along the direction A in which the tip of the C-shaped arm 7 protrudes with respect to the C-shaped arm 7 and can move forward and backward along the width direction S of the C-shaped arm 7. Yes.

  The X-ray tube shift mechanism 31 corresponds to the radiation source shift means of the present invention, and the X-ray tube shift control unit 32 corresponds to the radiation source shift control means of the present invention. Similarly, the FPD shift mechanism 33 corresponds to the detector shift mechanism of the present invention, and the FPD shift control unit 34 corresponds to the detector shift control means of the present invention.

  The configuration of the FPD shift mechanism 33 will be described. The actual configuration of the FPD shift mechanism 33 is a general xy stage. That is, in the initial state in which the C-type arm 7 is not inclined with respect to the top plate 2, the FPD 4 is independent of the width direction S of the C-type arm 7 and the protruding direction A of the tip of the C-type arm 7. Can move. The initial state of the C-type arm 7 refers to a state in which the X-ray tube 3 supported by the C-type arm 7 is positioned just vertically downward of the FPD 4. The FPD shift mechanism 33 has two guide rails extending in the protruding direction A of the tip of the C-type arm 7 and the width direction S of the C-type arm 7 in the initial state of the C-type arm 7. According to this guide rail, the FPD 4 moves in the direction A in which the tip of the C-type arm 7 projects and in the width direction S of the C-type arm 7.

  Similarly, the X-ray tube shift mechanism 31 is an xy stage. In an initial state in which the C-type arm 7 is not inclined with respect to the top plate 2, the X-ray tube 3 is independent of the width direction S of the C-type arm 7 and the protruding direction A of the tip of the C-type arm 7. Can move. Note that the X-ray tube shift mechanism 31 also has two guide rails similar to the FPD shift mechanism 33.

  Further, as shown in FIG. 1, the X-ray tomography apparatus 1 also includes a main control unit 24 that comprehensively controls the control units 6, 10, 12, 32, and 34. The main control unit 24 is constituted by a CPU, and realizes the control units 6, 10, 12, 32, and 34 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 tomography apparatus 1 according to the first embodiment includes a display unit 23 that displays an X-ray fluoroscopic image of the subject M.

  Next, the operation of such an X-ray tomography apparatus 1 will be described. FIG. 2 is a flowchart for explaining the operation of the radiation tomography apparatus according to the first embodiment. In order to obtain a tomographic image of a subject with the X-ray tomography apparatus 1 according to the first embodiment, the subject placement step S1 for placing the subject M on the top 2, the X-ray tube 3, and the FPD 4 Projecting first step S2 for projecting from the C-shaped arm 7; first rotating step S3 for acquiring an X-ray fluoroscopic image of the subject M while rotating the C-shaped arm 7 around the isocenter; and the X-ray tube 3 , And an FPD 4 projecting second step S4 for projecting from the C-type arm 7, and a rotating second step S5 for acquiring an X-ray fluoroscopic image of the subject M while rotating the C-type arm 7 around the isocenter, Each step of the reconstruction step S6 for reconstructing the acquired fluoroscopic image and acquiring a tomographic image of the subject M is performed. Details of each of these steps will be described in order with reference to the drawings. It is assumed that the C-arm 7 rotates around the central axis Q in FIG.

<Subject Placement Step S1 and Overhanging First Step S2>
First, the subject M is placed on the top 2. At this point, the surgeon acquires an X-ray fluoroscopic image of the subject M through the console 22 in a manner in which the C-arm 7 is rotated twice for the purpose of acquiring a tomographic image that requires a wide visual field. It is assumed that Then, the X-ray tomography apparatus 1 according to the first embodiment causes the X-ray tube 3 and the FPD 4 to protrude from the C-arm 7 through the X-ray tube shift control unit 32 and the FPD shift control unit 34. The direction in which the X-ray tube 3 and the FPD 4 protrude is the same direction, and both the X-ray tube 3 and the FPD 4 are shifted rearward in the width direction S of the C-arm 7. This situation is as shown in FIG.

<Rotation first step S3>
Next, the C-shaped arm 7 is rotated around the central axis Q (see FIG. 1). The X-ray tube 3 intermittently emits a radiation beam toward the FPD 4 while rotating, and the FPD 4 sends an X-ray detection signal to the image processing unit 15 each time. The image processing unit 15 acquires a series of X-ray fluoroscopic images based on this detection signal. The rear side of the C-arm 7 in the width direction S is a tangential direction of the rotational movement at the time of starting the rotation of the FPD 4 and is a traveling direction side at the time of starting the rotation. It is the tangential direction of the rotational movement and is on the opposite side of the traveling direction at the start of rotation. As can be seen from FIG. 4, the visual field range Ra in which the tomographic image at this time can be acquired is shifted rearward in the width direction S of the C-arm 7 with respect to the isocenter P. The isocenter P corresponds to a predetermined rotation center of the present invention.

<Overhanging second step S4 and rotation second step S5>
When the C-arm 7 rotates once, the X-ray tube 3 and the FPD 4 are both shifted forward in the width direction S of the C-arm 7. This situation is as shown in FIG. Then, the C-type arm 7 is rotated again around the isocenter. An X-ray fluoroscopic image is acquired at the time of this rotation, and the state thereof is the same as that in the first rotation step S3, so that the description thereof is omitted. In addition, the front of the C-arm 7 in the width direction S is a tangential direction of the rotational movement at the time of starting the rotation of the FPD 4 and is a traveling direction side at the time of starting the rotation. It is the tangential direction of the rotational movement and is on the opposite side of the traveling direction at the start of rotation. As can be seen from FIG. 6, the visual field range Rb in which the tomographic image at this time can be acquired is shifted forward in the width direction S of the C-arm 7 with respect to the isocenter P. That is, the visual field range Ra and the visual field range Rb are shifted from each other.

  In each rotation step S3, S5, the C-arm 7 is rotated around the isocenter P. Therefore, the C-arm 7 does not need to be complicatedly moved as in the prior art, and the control required for the first rotation step S3 and the second rotation step S5 is to rotate the C-arm 7 around the central axis Q. It is not necessary to move the column 8 at all. Furthermore, it is only necessary to acquire an X-ray fluoroscopic image while changing the positions of the X-ray tube 3 and the FPD 4, and the rotation direction of the C-arm 7 in each rotation step is merely an example. Even if the direction of rotation in each step is reversed, the tomographic image can be reconstructed.

<Reconfiguration step S6>
The X-ray fluoroscopic images acquired in the rotation steps S3 and S5 are sent to the reconstruction unit 16. In a series of X-ray fluoroscopic images, the internal structure of the subject is reflected while changing the position. Since the rotation angles of the X-ray tube 3 and the FPD 4 are known in advance, the reconstruction unit 16 can assemble a tomographic image of the subject M based on a series of X-ray fluoroscopic images. The visual field range of the tomographic image at this time is a region obtained by adding the visual field range Ra and the visual field range Rb that are shifted from each other. That is, the tomographic image capturing method according to the first embodiment can provide a tomographic image with a wider field of view. The reconstructed tomographic image is displayed on the display unit 23, and the acquisition of the tomographic image according to the first embodiment is completed.

  As described above, according to the configuration of the first embodiment, the FPD shift mechanism 33 is provided. The FPD shift mechanism 33 moves the FPD 4 forward and backward along the tangential direction of the rotational movement at the time of starting rotation and along the traveling direction side at the time of starting rotation. For example, the FPD 4 is projected from the C-arm 7 toward the traveling direction when the FPD 4 starts rotating. When the C-arm 7 is rotated around the isocenter in this state, the FPD shift mechanism 33 is rotated accordingly. However, since the FPD 4 protrudes from the C-type arm 7, the rotation center of the FPD 4 is different from the rotation center of the C-type arm 7. By doing so, the visual field region of the reconstructed tomographic image is also shifted. According to the configuration of the first embodiment, following the above-described rotation, the FPD 4 is projected from the C-arm 7 in the direction opposite to the rotation direction of the FPD 4 (the direction opposite to the protruding direction). When the C-arm 7 is rotated once again around the isocenter P in this state, the field area of the reconstructed tomographic image is shifted again along with the change of the projecting direction. If a single tomographic image is reconstructed using X-ray fluoroscopic images in the visual field range where the positions are shifted from each other, a tomographic image of the subject can be acquired over a wide range. The visual field range at this time is a new visual field range obtained by superimposing the visual field ranges. As described above, according to the configuration of the first embodiment, only by rotating the C-arm 7 about the isocenter twice, X-ray fluoroscopic images in the visual field range where the positions are shifted from each other can be acquired. Since the mold arm 7 does not need to perform a complicated movement such as moving in contact with the virtual circle, the control of the C-arm 7 rotation control unit is simple.

  Moreover, according to the structure of Example 1, the X-ray tube shift mechanism 31 is provided. The X-ray tube shift mechanism 31 moves the X-ray tube 3 forward and backward along the tangential direction of the rotational movement at the time of starting rotation and along the traveling direction side at the time of starting rotation. When the C-arm 7 is rotated twice around the isocenter, the X-ray tube 3 is also projected from the support means. Specifically, as shown in FIG. 3, when the FPD 4 protrudes from the C-arm 7 in the direction of travel at the time of rotation start, the X-ray tube shift mechanism 31 moves relative to the C-arm 7. The X-ray tube 3 is projected in the direction opposite to the traveling direction at the time of starting rotation. Similarly, as shown in FIG. 5, when the FPD 4 protrudes from the C-arm 7 in the direction opposite to the traveling direction at the time of starting rotation, the X-ray tube shift mechanism 31 is connected to the C-arm 7. In contrast, the X-ray tube 3 is projected in the direction of travel at the time of starting rotation. When the C-arm 7 rotates, the X-ray tube 3 and the FPD 4 rotate so as to follow each other, so the traveling direction side when the X-ray tube 3 starts rotating and the traveling direction side when the FPD 4 starts rotating. Are opposite to each other. That is, in the case of FIG. 3, the traveling direction side when the FPD 4 starts rotating and the opposite direction side when the X-ray tube 3 starts rotating are in the same direction. Further, in the case of FIG. 5, the same applies to the direction opposite to the direction of travel when the FPD 4 starts rotating and the direction of travel toward the start of rotation of the X-ray tube 3. Based on the above, the FPD 4 and the X-ray tube 3 project from the C-arm 7 in a state where the positional relationship between them is maintained. Therefore, the X-ray irradiated from the X-ray tube 3 is surely captured by the FPD 4.

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

  (1) In the embodiment described above, the C-arm 7 is rotated around the central axis Q parallel to the direction in which the two tips protrude, but the present invention is not limited to this. The present invention can also be applied by rotating the C-arm 7 around the center of curvature. In this case, the top plate 2 is inclined by 90 ° compared to the configuration of FIG. 1, and when the C-arm 7 is in the initial state, the protruding direction A of the C-arm 7 is determined by the subject M. In the body axis direction, the width direction S of the C-arm 7 is along the body side direction of the subject M. When the C-type arm 7 is rotated about the center of curvature, the FPD 4 and the X-ray tube 3 rotate around the body axis of the subject M while maintaining the relative positional relationship (arrow G in FIG. 7). reference). Even in this case, the X-ray tube 3 and the FPD 4 protrude from the C-arm 7. In FIG. 1, since the C-type arm 7 and the top plate 2 interfere with each other, the subject M cannot be freely brought close to the C-type arm 7, and the cutting position of the acquired tomographic image in the subject is limited. It becomes what was done. However, according to this modification, the body axis direction of the subject M is a direction that penetrates the C-type arm 7, so that the subject M and the C-type arm 7 can be moved by sliding the top 2. The position of can be changed freely.

  (2) In the embodiment described above, the X-ray tube shift mechanism 31 and the FPD shift mechanism 33 are xy stages, but the present invention is not limited to this. A similar configuration can be made using a single guide. That is, the FPD shift mechanism 33 of the present modification includes two rails 33a extending in the direction of extending the tip of the C-arm 7 as shown in FIG. 8, and a sliding plate 33b guided by the rails 33a. A sliding plate controller 43b for controlling the sliding of the sliding plate, a first rotating shaft 33c connected to the sliding plate 33b, a linear arm 33d extending from the first rotating shaft 33c, and a tip of the linear arm 33d. The second rotation shaft 33e is provided. The second rotating shaft 33e is connected to the FPD 4.

  Each of the first rotating shaft 33c and the second rotating shaft 33e includes a first rotating shaft driving unit 42c that drives the first rotating shaft 33c and a second rotating shaft driving unit 42e. They are controlled by the first rotating shaft drive control unit 43c and the second rotating shaft drive control unit 43e. The linear arm 33d is rotated around the sliding plate 33b by the first rotating shaft drive part 42c. In addition, the angle between the FPD 4 and the linear arm 33d can be changed by the second rotating shaft driving unit 42e. As the sliding plate 33b slides while being guided by the rail 33a, the FPD 4 can advance and retract in the direction in which the tip of the C-arm 7 protrudes. The state of advancement / retraction of the FPD 4 is indicated by an arrow J in FIG.

  Further, the position of the FPD 4 can be changed with respect to the width direction S of the C-arm 7. In this case, the inclination angle of the linear arm 33d with respect to the C-arm 7 is changed. This change is made by the first rotating shaft driving unit 42c. As a result, the FPD 4 advances and retreats in the width direction S of the C-arm 7 (arrow K in FIG. 8). At the same time, the inclination angle of the FPD 4 with respect to the linear arm 33d is changed. This change is made by the second rotating shaft driving unit 42e. Since the FPD 4 moves in an arcuate shape, the position of the FPD 4 is changed in the direction in which the tip of the C-type arm 7 protrudes. By advancing and retracting in the direction in which the tip protrudes, the position of the FPD 4 in the direction in which the tip of the C-arm 7 of the FPD 4 protrudes is kept constant. Moreover, unlike the xy stage, it is not necessary to provide rails that extend in different directions, and the mechanism itself can be simplified. Thereby, the C-type arm 7 can be set small, and the apparatus can be made lightweight.

  (3) In the above-described embodiment, the X-ray tube 3 protrudes from the C-arm 7. However, the present invention is not limited to this. That is, as shown in FIG. 9, an X-ray tube tilting mechanism 35 and an X-ray tube tilt control unit 36 for controlling the X-ray tube tilting mechanism 35 may be provided at a position between the X-ray tube 3 and the C-arm 7. . The X-ray tube tilting mechanism 35 tilts the X-ray tube 3 along the tangential direction of the rotational movement at the time of starting rotation. Specifically, when the C-arm 7 is rotated twice around the isocenter, the X-ray tube 3 is tilted toward the X-ray tube tilting mechanism 35. First, as shown in FIG. 9, when the FPD 4 protrudes from the C-type arm 7 in the traveling direction at the time of starting rotation, the X-ray tube tilting mechanism 35 3 is inclined in the direction opposite to the traveling direction at the time of starting rotation. Similarly, as shown in FIG. 10, when the FPD 4 protrudes from the C-arm 7 in the direction opposite to the traveling direction at the time of starting rotation, the X-ray tube tilting mechanism 35 is connected to the C-arm 7. In contrast, the X-ray tube 3 is inclined toward the traveling direction at the time of starting rotation. When the C-arm 7 rotates, the X-ray tube 3 and the FPD 4 rotate so as to follow each other, so the traveling direction side when the X-ray tube 3 starts rotating and the traveling direction side when the FPD 4 starts rotating. Are opposite to each other. That is, in the case of FIG. 9, the traveling direction side when the FPD 4 starts rotating and the opposite direction side when the X-ray tube 3 starts rotating are in the same direction. Further, in the case of FIG. 10, the same applies to the direction opposite to the direction of travel when the FPD 4 starts rotating and the direction of travel toward the start of rotation of the X-ray tube 3. In view of the above, the X-ray tube 3 faces the FPD 4 side regardless of which direction the FPD 4 protrudes from the C-arm 7. Therefore, the X-ray irradiated from the X-ray tube 3 is surely captured by the FPD 4.

  (4) 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.

  (5) 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.

  (6) In the embodiment described above, the X-ray tomography apparatus 1 is provided with the single C-shaped 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.

  (7) Each embodiment described above is a medical device, but the present invention can also be applied to industrial and nuclear devices.

  (8) The X-ray referred to in each of the above-described embodiments is an example of radiation in the present invention. Therefore, the present invention can be applied to radiation other than X-rays.

1 X-ray tomography equipment (radiation tomography equipment)
3 X-ray tube (radiation source)
4 FPD (radiation detection means)
7 C-type arm (support member)
12 C-type arm rotation control unit (support member rotation control means)
16 Reconstruction unit (tomographic image acquisition means)
31 X-ray tube shift mechanism (radiation source shift means)
32 X-ray tube shift control unit (radiation source shift control means)
33 FPD shift mechanism (detector shift means)
34 FPD shift control unit (detector shift control means)
35 X-ray tube tilt mechanism (radiation source tilting means)
36 X-ray tube tilt control unit (radiation source tilt control means)

Claims (3)

A radiation source for irradiating the radiation beam; a radiation detection means for detecting the radiation beam; a support member for supporting the radiation source and the radiation detection means; and rotating the support member about a predetermined rotation center. In the radiation tomography apparatus comprising: a support member rotation control unit that rotates and moves the radiation source and the radiation detection unit; and a tomographic image acquisition unit that acquires a tomographic image;
The radiation detection means is provided at a position where the support member and the radiation detection means are interposed, and the radiation detection means is moved forward and backward along a tangential direction of rotational movement at the time of starting rotation thereof, thereby moving the radiation detection means to the support member. (A) detector shift means for projecting in the direction of either the traveling direction at the start of rotation of the radiation detecting means or (B) the opposite direction side;
Detector shift control means for controlling the detector shift means,
The detector shift control means causes the radiation detection means to protrude toward one direction of either (A) or (B), and the radiation source and the radiation detection means are maintained in this state. And rotate and move to obtain multiple radioscopic images,
Subsequently, the detector shift control means causes the radiation detection means to protrude in the direction opposite to the one direction, and the radiation source and the radiation detection means are rotated while maintaining this state. While acquiring multiple radiographic images,
The radiation tomography apparatus according to claim 1, wherein the tomographic image acquisition unit acquires a tomographic image based on the acquired radioscopic image. The radiation tomography apparatus according to claim 1,
The radiation source is provided at a position where the support member and the radiation source are interposed, and the radiation source is moved forward and backward along the tangential direction of the rotational movement at the time of starting the rotation, whereby the radiation source is moved with respect to the support member. (C) Radiation source shift means for projecting in either the traveling direction side at the start of rotation of the radiation source or (D) the opposite direction side thereof;
Radiation source shift control means for controlling the radiation source shift means,
When the radiation detection means projects to the support member (A) in the direction of travel when the radiation detection means starts to rotate, the radiation source shift means causes the radiation source to move relative to the support member ( D) projecting to the opposite side of the traveling direction at the start of rotation of the radiation source,
When the radiation detection means projects to the support member (B) in the direction opposite to the advancing direction at the start of rotation of the radiation detection means, the radiation source shift means causes the radiation source to be placed on the support member. On the other hand, (C) a radiation tomography apparatus characterized by projecting toward the traveling direction side when the radiation source starts rotating. The radiation tomography apparatus according to claim 1,
The radiation source is provided at a position where the support member and the radiation source are interposed, and the radiation source is inclined with respect to the support member by tilting the radiation source. Or (N) a radiation source tilting means for tilting in any direction side of the opposite direction side,
Radiation source tilt control means for controlling the radiation source tilt means,
When the radiation detection means projects to the support member (A) in the advancing direction at the start of rotation of the radiation detection means, the radiation inclination means causes the radiation source to (N ) Inclined to the opposite side of the traveling direction at the start of rotation of the radiation source,
When the radiation detection means projects to the support member (B) in the direction opposite to the traveling direction when the radiation detection means starts rotating, the radiation tilting means causes the radiation source to be directed to the support member. (M) A radiation tomography apparatus, wherein the radiation source is tilted toward the traveling direction at the start of rotation of the radiation source.

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