JP2006263052A - Radiographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radiographic equipment capable of surely preventing interference fringes. <P>SOLUTION: When radiographing a subject by reciprocatingly moving an X-ray grid 4 in the longitudinal direction H<SB>H</SB>of a top board 1, this radiographic equipment is so formed as to reciprocatingly move the X-ray grid 4 in the short-side direction H<SB>V</SB>of the top board by rotating the X-ray grid 4 by a driving part 5. That is to say, when radiographing the subject by reciprocatingly moving the X-ray grid 4 in the longitudinal direction H<SB>H</SB>in a state where the X-ray grid 4 is disposed in such a manner as disposing the streaks of a metal piece 4a along the longitudinal direction H<SB>H</SB>, this equipment can prevent the interference fringes in the image. On the other hand, when the X-ray grid 4 is rotated from the longitudinal direction H<SB>H</SB>to the short side direction H<SB>V</SB>for disposing the streaks of the metal piece 4a along the short-side direction H<SB>V</SB>and reciprocatingly moved in the short-side direction H<SB>V</SB>, this equipment can surely prevent the interference fringes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radiation imaging apparatus used in the medical field, industrial fields such as non-destructive inspection, RI (Radio isotope) inspection, and optical inspection, and nuclear power field, and in particular, detected by a flat panel type radiation detection means. The present invention relates to a technique for imaging based on emitted radiation.

  An X-ray diagnostic apparatus will be described as an example of the radiation imaging apparatus. An X-ray diagnostic apparatus uses an image intensifier (hereinafter referred to as “I.I” as appropriate) to detect X-rays transmitted through a subject. In general, the longitudinal direction of the top plate on which the subject is placed has the highest degree of freedom, so that it can be reciprocated in the longitudinal direction of the top plate. In the case of tomography, it is performed while moving in the longitudinal direction of the top plate.

However, in the case of tomographic imaging, the resolution tends to decrease with respect to the tomographic direction. This will be described with reference to FIG. An X-ray tube 102 for irradiating the subject M with X-rays in the longitudinal direction H _H of the top plate 101 on which the subject M is placed; I103 is reciprocated. For example, when the imaging part is the chest of the subject M and tomography is performed with the center of the lung in the chest as the center, the X-ray tube 102 and the center of the lung are centered on the X-ray. I. I103 is made to oppose. The X-ray tube 102 is moved in the direction of the arrow in the figure in the longitudinal direction H _H , I103 is moved in the direction of the arrow in the figure in the longitudinal direction. Further, the top plate 101 is moved in the longitudinal direction H _H to move the subject M on the top plate 101. When performing tomography in this way, I103 moves in a direction opposite to the moving direction of the X-ray tube. Assuming that the tomographic direction of the tomographic image obtained at this time is V, the resolution gradually decreases as the distance from the center of the lung in the tomographic direction V (that is, the vertical direction) increases.

In recent years, in order to solve such a problem, a flat panel X-ray detector (hereinafter referred to as “FPD” as appropriate) is used to detect X-rays transmitted through a subject. This FPD is an I.D. It is lighter than I and thinner in thickness. The degree of freedom is higher than I. Therefore, not only to move the FPD104 longitudinally H _H as shown in FIG. 5 (a), it is also possible to move the FPD104 in the lateral direction H _V as shown in Figure 5 (b). By collecting tomographic images of the same cut surface C from these two directions, a reduction in resolution can be prevented and more detailed diagnosis can be performed. In addition, since imaging can be performed in two directions, diagnosis can be performed by moving only the X-ray tube 102 and the FPD 104 while the subject on the top plate 101 is stationary. Therefore, it is possible to cope with diagnosis such as IVR (Interventional Radiology) for performing treatment while performing diagnosis and endoscope.

By the way, by providing an X-ray grid for removing scattered X-rays on the detection surface side of the FPD, deterioration of image quality such as a fluoroscopic image and a tomographic image due to scattered X-rays is prevented (for example, see Patent Document 1). Further, in order to prevent the appearance of interference fringes in the image, the X-ray grid is reciprocated in the same direction as the movement direction of the FPD.
Japanese Patent Laid-Open No. 05-137715

However, as shown in the plan view of FIG. 6A, in the X-ray grid 105, metal pieces 105a in which lead (Pb) and aluminum (Al) are alternately arranged are arranged in parallel at short intervals. Therefore, in order to reliably prevent interference fringes, it is preferable to reciprocate the X-ray grid 105 in a parallel direction along the direction (stripe) in which the metal piece 105a extends. For example, in the case where the X-ray grid 105 is reciprocated in the longitudinal direction of the top plate 101, as shown in the plan view of FIG. 6 (b), so that the metal piece 105a extends along the longitudinal direction H _H An X-ray grid 105 is disposed on the screen. Thus, when reciprocating the FPD104 also in the lateral direction H _V of the top plate 101 as shown in FIG. 5 (b), also the X-ray grid for reciprocating the transverse direction, the metal piece 105a is extended The existing direction (stripe) becomes a direction orthogonal to the short direction, and interference fringes cannot be reliably prevented. Thus, in order to prevent interference fringes with certainty, it is necessary to make the direction in which the scattered radiation removal means represented by the X-ray grid can reciprocate freely.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation imaging apparatus that can reliably prevent interference fringes.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention described in claim 1 is a flat panel type radiation detecting means for detecting radiation that has passed through the subject, and radiation that is arranged in parallel to the detection surface of the flat panel type radiation detecting means and that is scattered. And the scattered radiation removing means removes the scattered radiation while the scattered radiation removing means reciprocates in one direction in a parallel plane parallel to the detection surface. Is a radiation imaging apparatus that images a subject based on the detected radiation, and includes a rotating means for rotating scattered radiation removing means within the parallel plane. .

  [Operation / Effect] According to the invention described in claim 1, the radiation scattered by the scattered radiation removing means reciprocating in one direction in a parallel plane parallel to the detection surface of the flat panel radiation detecting means. When the flat panel type radiation detection means detects radiation with the image removed, and the subject is imaged based on the detected radiation, interference fringes appearing in the image obtained by the imaging are prevented. be able to. In order to prevent interference fringes in other directions in the parallel plane, the rotating means can freely move the scattered radiation removing means in a reciprocating direction by rotating the scattered radiation removing means in the parallel plane. It becomes possible to change to. As a result, the interference fringes can be reliably prevented by rotating the scattered radiation removing means by the rotating means in a direction in which the interference fringes do not appear and reciprocating.

  An example of the invention described above is as follows. That is, when imaging the subject while the scattered radiation removing means reciprocates in the longitudinal direction of the top plate with the top plate on which the subject is placed arranged parallel to the detection surface, the rotating means By rotating the scattered radiation removing means, the scattered radiation removing means and the rotating means are configured so that the scattered radiation removing means can be reciprocated in the short direction of the top plate. Described invention). In this case, when the subject is imaged while the scattered radiation removing means reciprocates in the longitudinal direction of the top plate, interference fringes appearing in the image obtained by the imaging are prevented. On the other hand, even when the scattered radiation removing means is reciprocated by rotating it from the longitudinal direction to the short direction by the rotating means so that the interference fringes do not appear, It can be surely prevented.

  In each of the above-described inventions, it is preferable to configure the rotating means so that the scattered radiation removing means stops rotating at an arbitrary position (the invention according to claim 3). With this configuration, moire removal can be performed at an arbitrary position while the scattered radiation removing unit is stationary.

  According to the radiation imaging apparatus of this invention, the rotating means can reciprocate the scattered radiation removing means by rotating the scattered radiation removing means in a parallel plane parallel to the detection surface of the flat panel radiation detecting means. It is possible to freely change any direction by the rotating means. As a result, the interference fringes can be reliably prevented by rotating the scattered radiation removing means by the rotating means in a direction in which the interference fringes do not appear and reciprocating.

Embodiments of the present invention will be described below with reference to the drawings.
1 is a front view showing a schematic configuration of the X-ray diagnostic apparatus according to the embodiment, FIG. 2 is a side view thereof, and FIG. 3A is a plan view of the periphery of the top board. (B) is a top view of the periphery of a top plate when rotating an X-ray grid. In the present embodiment, an X-ray diagnostic apparatus will be described as an example of a radiation imaging apparatus.

As shown in FIG. 1, the X-ray diagnostic apparatus according to the present embodiment includes a top plate 1 on which a subject M is placed, an X-ray tube 2 that irradiates the subject M with X-rays, and a subject. A flat panel X-ray detector (hereinafter referred to as “FPD” as appropriate) 3 that detects X-rays transmitted through M is provided. The X-ray tube 2 and the FPD 3 are configured to move independently of each other, and the X-ray bundle irradiated from the X-ray tube 2 is configured to pass through the center of the FPD 3. Therefore, as shown in FIG. 1, when tomography is performed by moving the top plate 1 in the longitudinal direction H _H , the FPD 3 moves in a direction opposite to the moving direction of the X-ray tube 2. In this embodiment, as shown in FIG. 2, X-ray tube 2 and FPD3 to allow even tomography is moved in the lateral direction H _V of the top plate 1 is constructed. Even in this case, the FPD 3 moves in the direction opposite to the moving direction of the X-ray tube 2. The FPD 3 corresponds to the flat panel type radiation detecting means in this invention.

  An X-ray grid 4 for removing scattered X-rays is disposed adjacent to and parallel to the detection surface side (X-ray irradiation side) of the FPD 3. As shown in FIG. 3, the X-ray grid 4 is formed by arranging metal pieces 4a in which lead (Pb) and aluminum (Al) are alternately arranged in parallel at a short interval, and scattered X-rays. Is blocked by lead. By providing such an X-ray grid 4, deterioration of image quality such as a fluoroscopic image and a tomographic image due to scattered X-rays is prevented. The X-ray grid 4 corresponds to the scattered radiation removing means in this invention.

Such an X-ray grid 4 is reciprocated in the same direction as the movement direction of the FPD 3 at a distance of about several millimeters with a period of about 1 Hz, for example, thereby preventing interference fringes appearing in the image. For example, as shown in FIG. 1, when tomography is performed by moving the top plate 1 in the longitudinal direction H _H , the X-ray grid 4 is also moved back and forth in the longitudinal direction H _H. metal piece 4a in the longitudinal direction H _H as shown to provided an X-ray grid 4 so as to extend. In other words, so that fringes of the metal pieces 4a are disposed along the X-ray grid 4 in a longitudinal direction H _H reciprocate.

On the other hand, since, even X-ray grid 4 is reciprocated in the lateral direction H _V when moved in the lateral direction H _V of the top plate 1 as shown in FIG. 2 perform tomography, FIG 3 (b ) are shown as along the widthwise direction H _V arranging the X-ray grid 4 such that the metal piece 4a extends. In other words, so that fringes of the metal pieces 4a are disposed along the X-ray grid 4 in the lateral direction H _V for reciprocating.

  In this embodiment, the arrangement state of the X-ray grid 4 shown in FIG. 3A and the arrangement state of the X-ray grid 4 shown in FIG. ), And a drive unit 5 shown in FIG. The drive unit 5 rotates the X-ray grid 4 in a parallel plane (horizontal plane in this embodiment) that is parallel to the detection plane of the FPD 3. Therefore, when the driving unit 5 rotates the X-ray grid 4 90 degrees clockwise (clockwise) from the arrangement state shown in FIG. 3A, the state changes to the arrangement state shown in FIG. Conversely, when the driving unit 5 rotates the X-ray grid 4 90 degrees counterclockwise (counterclockwise) from the arrangement state shown in FIG. 3B, the arrangement state is changed to the arrangement state shown in FIG. . Further, the drive unit 5 is not limited to 90 ° rotation, and in the case of the present embodiment, the X-ray grid 4 is rotated at an arbitrary angle from 0 ° to 90 °, and the rotation is performed at an arbitrary position. Configured to stop. The drive unit 5 corresponds to the rotating means in this invention.

A combination of these longitudinal H _H and lateral direction H _V in the case of performing the tomography is performed as follows. When performing tomography in the longitudinal direction H _H, the FPD 3 detects X-rays irradiated from the X-ray tube 2 and transmitted through the subject M while moving the X-ray tube 2 and the FPD 3 as shown in FIG. To do. At this time, X-rays the grid 4 with longitudinal movement H _H of FPD3 also while moving so as to follow the longitudinal direction H _H, it is also reciprocally moved in the longitudinal direction H _H at a distance of several mm at a period of about 1 Hz.

When performing tomography widthwise direction H _V is the FPD 3 while moving the X-ray tube 2 and FPD 3, is irradiated from the X-ray tube 2 the X-rays transmitted through the patient M as shown in FIG. 2 To detect. In this case, likewise reciprocating in the lateral direction H _V in the lateral direction H _V X-ray grid 4 with the movement of even while moving to follow the lateral direction H _V, the distance of several mm at a period of about 1Hz the FPD3 Moving.

Note that the order of tomographic imaging in the longitudinal direction H _H and the short direction H _V is not particularly limited, and the tomographic imaging in the lateral direction H _V may be performed after the longitudinal direction H _H is performed first, may be performed tomography longitudinally H _H after the lateral direction H _V above. May also be carried out alternately tomography longitudinal H _H and the lateral direction H _V.

According to the apparatus of this embodiment configured as described above, the X-ray grid 4 reciprocates in a certain direction (longitudinal direction H _H in this embodiment) in a horizontal plane parallel to the detection surface of the FPD 3. When the FPD 3 detects the X-rays with the scattered X-rays removed, and the subject M is imaged based on the detected X-rays, an image obtained by the imaging (a tomographic image in this embodiment) is obtained. ) Interference fringes appearing inside can be prevented. In order to prevent interference fringes in other directions (short direction H _V in this embodiment) in the horizontal plane, the drive unit 5 rotates the X-ray grid 4 in the horizontal plane to The reciprocable direction can be freely changed by the drive unit 5. As a result, the interference fringes are reliably prevented by rotating the X-ray grid 4 by the drive unit 5 and reciprocatingly moving it in the direction in which the interference fringes do not appear as shown in FIG. 3 (a) or FIG. 3 (b). can do.

In this embodiment, the top plate 1 on which the subject M is placed is arranged in parallel to the detection surface, and the X-ray grid 4 reciprocates in the longitudinal direction H _H of the top plate 1 while when performing imaging, drive unit 5 by rotating the X-ray grid 4, the X-ray grid 4 an X-ray grid 4 and driven so as to reciprocate in the lateral direction H _V of the top plate 1 Each part 5 is configured. In this case, while disposed in the X-ray grid 4 as fringes metal piece 4a in the longitudinal direction H _H is disposed, moves the X-ray grid 4 in a longitudinal direction H _H of the top plate 1 is reciprocally However, when the subject M is imaged, interference fringes appearing in the image obtained by the imaging are prevented. On the other hand, so that the interference fringes does not appear, i.e. the lateral direction from the longitudinal H _H X-ray grid 4 by the drive unit 5 so as to be arranged fringes metal piece 4a along the widthwise direction H _V by reciprocating by rotating the H _V, even when is reciprocated in the lateral direction H _V, it is possible to reliably prevent interference fringes.

  Further, by configuring the drive unit 5 to stop the rotation of the X-ray grid 4 at an arbitrary position, it is possible to remove moire at an arbitrary position while the X-ray grid 4 is stationary.

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

  (1) In the above-described embodiment, the X-ray diagnostic apparatus as shown in FIG. 1 has been described as an example. However, the present invention is also applied to an X-ray diagnostic apparatus disposed on a C-type arm, for example. Also good. Further, the present invention is not limited to medical use, and may be applied to industrial devices such as nondestructive inspection equipment.

(2) In the embodiment described above, the top plate 1 is arranged in a horizontal posture as shown in FIG. 1, and the detection surface of the FPD 3 is arranged in a horizontal plane, and the longitudinal direction H _H and the short direction in the horizontal plane. the X-ray grid 4 in H _V was reciprocated but not limited horizontally. For example, the top plate is placed in a standing posture, and the FPD is also placed in a standing posture so that the detection surface is parallel to the top plate. You may let them. Note that even when imaging is performed, the FPD or the like is reciprocated in the longitudinal direction and the lateral direction within the standing surface. The same applies when imaging is performed in an oblique posture between the horizontal posture and the standing posture.

(3) In the foregoing embodiment, although a like longitudinal H _H and lateral direction H _V to FPD3 and the X-ray grid 4 of the top plate 1 is reciprocated as shown in FIGS. 1 and 2, reciprocating The direction is not particularly limited. When imaging is performed so as to cross the top plate 1 in an oblique direction, the FPD 3 or the X-ray grid 4 may be reciprocated in correspondence with the oblique direction.

  (4) In the above-described embodiment, the rotation of the X-ray grid 4 is stopped at an arbitrary position in order to perform moire removal. However, when the moire removal is not performed, the X-ray grid 4 is not necessarily rotated at an arbitrary position. There is no need to stop.

  (5) In the embodiment described above, tomography was performed from two directions, the longitudinal direction and the lateral direction, but it is also possible to perform an arc tomography of the X-ray tube by combining both the longitudinal direction and the lateral direction. It is.

  (6) In the above-described embodiment, a flat panel X-ray detector that detects X-rays has been described as an example. However, the present invention provides a radioisotope (RI) as in an ECT (Emission Computed Tomography) apparatus. There is no particular limitation as long as it is a flat panel radiation detector that detects radiation, as exemplified by a γ-ray detector that detects γ-rays radiated from a subject to which is administered. Similarly, the present invention is not particularly limited as long as it is an apparatus that performs imaging by detecting radiation, as exemplified by the ECT apparatus described above.

It is a front view which shows schematic structure of the X-ray diagnostic apparatus which concerns on an Example. It is a side view of FIG. (A) is a top view of the periphery of a top plate, (b) is a top view of the periphery of a top plate when rotating an X-ray grid. It is a figure which shows the imaging aspect when using an image intensifier (II) conventionally. It is a figure which shows the imaging aspect when a flat panel type | mold X-ray detector (FPD) is used conventionally, (a) is a front view, (b) is a side view. (A) is a front view of an X-ray grid, (b) is a plan view showing the arrangement of the X-ray grid.

Explanation of symbols

1 ... Top plate 3 ... Flat panel X-ray detector (FPD)
4 ... X-ray grid 5 ... Drive unit H _H ... Longitudinal direction (top plate) H _V ... Short direction (top plate) M ... Subject

Claims (3)

  A flat panel type radiation detecting means for detecting radiation transmitted through the subject; and a scattered radiation removing means arranged in parallel to a detection surface of the flat panel type radiation detecting means and for removing scattered radiation, The flat panel type radiation detection means detects the radiation while the scattered radiation removal means removes the scattered radiation while reciprocating in one direction in the parallel plane parallel to the detection surface, and the detected radiation is converted into the detected radiation. A radiation imaging apparatus for imaging a subject based on the radiation imaging apparatus, comprising: a rotating means for rotating a scattered radiation removing means within the parallel plane.   2. The radiation imaging apparatus according to claim 1, wherein the scattered radiation removing means reciprocally moves in the longitudinal direction of the top plate in a state where the top plate on which the subject is placed is arranged in parallel to the detection surface. When imaging the sample, the rotating means rotates the scattered radiation removing means, so that the scattered radiation removing means can be moved back and forth in the short direction of the top plate, and the scattered radiation removing means and the rotating means. A radiation imaging apparatus comprising: 3. The radiation imaging apparatus according to claim 1, wherein the rotating unit is configured to stop the rotation of the scattered radiation removing unit at an arbitrary position.

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