JP2006192164A - Radiographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems by removing scattered rays caused by relative movement of a radiation detector and a grid in a simple constitution in equipment radiographing a subject by integrally rotating an imaging system comprising an X-ray tube and a radiation detector disposed oppositely to each other. <P>SOLUTION: This radiographic equipment is provided with the imaging system consisting of the X-ray tube applying radiation to the subject and the two-dimensional radiation detector detecting the radiation transmitting through the subject, which are oppositely disposed in the both sides of the subject, applies the radiation to the subject while integrally rotating the imaging system and detects the radiation projected image of the subject by the radiation detector. This radiographic equipment is disposed with a grid into a tubular shape surrounding the body axis of the subject, the X-ray tube in a space sandwiched in between the subject and the grid, and the radiation detector in an outside space of the grid disposed in the tubular shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus using radiation, and more particularly to a structure and arrangement of a grid for removing scattered rays of a subject incident on a radiation detector.

  An imaging system consisting of a radiation tube and a radiation detector arranged opposite to each other is arranged oppositely across the subject, and radiation is directed toward the subject while rotating the imaging system integrally, and a radiation projection image of the subject is obtained. In imaging devices that detect radiation detectors, a fixed grid method is known in which scattered radiation is removed using a grid that is stationary in front of the radiation incident surface of a radiation detector composed of a plurality of detection elements. ing. (For example, refer to Patent Document 1).

  Further, in the conventional imaging apparatus using radiation, a moving grid method is known in which scattered radiation is removed by moving the grid relative to the radiation detector. This method prevents reflection of the X-ray shielding member on the projected image of the subject by spatially blurring the radiation projection image of the X-ray shielding member constituting the grid, which is imaged by the radiation detector. (For example, refer to Patent Document 2).

Japanese Patent Laid-Open No. 4-336044 (page 2, FIG. 1, FIG. 2, FIG. 4) JP-A-1-238644 (page 2)

  Although the method of removing the scattered radiation by fixing the grid to the radiation detector does not require a grid moving mechanism, the relative position between the detection element constituting the radiation detector and the X-ray shielding member constituting the grid If the relationship is not uniform over the entire surface of the radiation detection area, the amount of radiation incident on each detection element varies from detection element to detection element, resulting in unevenness and interference fringes in the acquired image. Therefore, there is a problem that manufacturing that maintains the uniformity of the grid and accurate arrangement with respect to the radiation detector are necessary.

  On the other hand, when the method of moving the grid with respect to the radiation detector and removing the scattered radiation is applied to an imaging apparatus that integrally rotates an imaging system composed of a radiation tube and a radiation detector, the grid and its moving mechanism It must be integrated with a rotating imaging system, which increases the complexity and size of the apparatus and increases the cost.

  Therefore, the problem described above is becoming an increasingly important issue as the detection size of the radiation detector increases in manufacturing.

  The present invention has been made in view of the above problems, and an object thereof is an apparatus for photographing a subject while integrally rotating an imaging system including a radiation tube and a radiation detector arranged to face each other. The object of the present invention is to realize the removal of scattered radiation by the relative movement of the radiation detector and the grid with a simple configuration and to solve the above-mentioned problems.

  According to a first aspect of the present invention for solving the above-described problem, an imaging system comprising a radiation tube for irradiating a subject with radiation and a two-dimensional radiation detector for detecting radiation transmitted through the subject is opposed to each other with the subject interposed therebetween. In a radiation imaging apparatus that arranges and irradiates a subject with radiation while rotating the imaging system integrally and detects a radiation projection image of the subject with the radiation detector, the grid is surrounded by the body axis of the subject The radiation tube is disposed in a cylindrical shape, the radiation tube is disposed in a space between the subject and the grid, and the radiation detector is disposed in a space outside the grid disposed in a cylindrical shape.

  According to the present invention, an X-ray CT imaging apparatus according to the present invention that performs imaging by integrally rotating an imaging system composed of a radiation tube and a radiation detector arranged opposite to each other with a subject interposed therebetween, the radiation detector, the grid, The scattered radiation can be removed by the relative movement without any movement of the grid.

  Accordingly, the apparatus is not complicated and does not increase in size, and manufacturing that maintains the uniformity of the grid and accurate arrangement with respect to the radiation detector are not required, and the cost does not increase.

<Embodiment 1>
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  In the following embodiments, an X-ray CT imaging apparatus that captures a tomographic image of a subject using X-rays will be described as an example of the radiation imaging apparatus of the present invention. However, the present invention is imaged using other radiation. It is also possible to apply to an apparatus.

  FIG. 1 is a front view illustrating a schematic configuration of the X-ray CT imaging apparatus according to the first embodiment, and FIG. 2 is a cross-sectional view of the schematic configuration viewed from the lateral direction.

  In the X-ray CT imaging apparatus, an X-ray tube 2 that irradiates X-rays and a two-dimensional X-ray detector 3 that detects X-rays are integrally held by a connecting member (not shown) and face each other. The arranged photographing system 1 is configured. Between the X-ray tube 2 and the X-ray detector 3, a top plate 5 on which the subject 4 lies is disposed by a support member (not shown).

  A grid 7 is arranged in a cylindrical shape by a support member (not shown) so as to surround the body axis 6 of the subject 4, that is, the axis extending in the direction perpendicular to the paper surface of FIG. 1 and the X-ray tube 2. A is the same as or wider than the width B of the X-ray detector 3. Therefore, only the X-ray detector 3 is arranged outside the cylindrical grid 7, and a part of the cylindrical grid 7 is arranged between the X-ray detector 3 and the subject 4. Become. The structure of the grid 7 is the same as that of the prior art, and has an X-ray shielding member 8 extending in the direction perpendicular to the paper surface of FIG. 1, for example, a lead foil, which are arranged at predetermined intervals.

  When the subject 4 is imaged, X-rays are emitted from the X-ray tube 2 toward the subject 4 while the imaging system 1 rotates integrally around the subject 4 by a rotation drive mechanism (not shown). Then, the X-ray detector 3 detects X-rays transmitted through the subject 4 and the grid 7 every predetermined time, and projection image data from the 360 ° direction is collected. A predetermined tomographic image is obtained by reconstructing the image data in an image processing apparatus (not shown) different from the imaging apparatus of the present invention.

  Here, the grid 7 passes only the X-rays that pass straight through the subject 4 from the X-ray tube 1 and passes the X-rays scattered by the subject 4 by the X-ray shielding member 8. Only an X-ray projection image is formed. Moreover, the imaging system 1 captures the subject 4 while rotating in the direction orthogonal to the direction in which the X-ray shielding member 8 of the grid 7 extends, that is, in the direction of the arrow in FIG. The same scattered ray removal effect as that obtained when the image is taken while relatively moving 7 can be obtained.

As described above, in the present embodiment, an image equivalent to the moving grid method can be acquired by moving the grid without changing the grid, by the structure, shape, and arrangement of the grid.
<Embodiment 2>
FIG. 3 is a front view showing a schematic configuration of the X-ray CT imaging apparatus according to the second embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the schematic configuration seen from the lateral direction. The same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In addition to the configuration of the embodiment, the X-ray CT imaging apparatus of the present embodiment includes a guide member 9 that supports the grid 7 so as to be movable a predetermined distance in a direction parallel to the body axis 6 of the subject 4. As the guide member 9, a linear guide device having a structure in which the movable rail is slidable by rolling and guiding the movable rail using a steel ball as a rolling element is used.

  The width of the grid 7 is wider to one side than that of the first embodiment, and the portion is disposed outside the X-ray detector 3 and is fixed to the movable rail 9a of the linear motion guide device. Three guide members 9 are arranged around the grid 7 at intervals of 120 degrees to support the grid 7 evenly. Then, under the guidance of the guide member 9, the grid 7 moves from the front of the X-ray detector 3 to the left in FIG. 4, that is, in the direction of the arrow, and is completely retracted from the front of the X-ray detector 3. It becomes possible to arrange.

  As described above, in this embodiment, not only the same effects as in the first embodiment can be obtained, but also the grid is not used when photographing the extremities and the chest, which are regions where the occurrence of scattered glands is relatively small. Shooting is also possible. Accordingly, among the X-rays that pass straight through the subject 4 from the X-ray tube 1 and are absorbed by the X-ray shielding member 8 of the grid 7, the X-ray projection image information of the subject 4 can also be used. The irradiation dose to the subject can also be reduced, which is particularly beneficial when the subject is a human body.

  In the above-described embodiment of the present invention, the X-ray shielding member 8 configured inside the grid 7 extends in a direction orthogonal to the rotation direction of the imaging system 1, but is not necessarily orthogonal. If the direction of rotation of the photographing system 1 does not coincide, the same effect can be obtained.

  Further, the photographing apparatus in which the subject 4 is lying on the top plate 5 is not limited, and the photographing system in which the photographing system 1 and the subject 4 are upright, that is, the schematic configuration when the photographing device is viewed from the ceiling is shown in FIGS. It is also applicable to cases.

1 is a front view illustrating a schematic configuration of an X-ray CT imaging apparatus according to Embodiment 1 of the present invention. It is sectional drawing explaining schematic structure of the X-ray CT imaging apparatus which concerns on Embodiment 1 of this invention. It is a front view explaining schematic structure of the X-ray CT imaging apparatus which concerns on Embodiment 2 of this invention. It is sectional drawing explaining schematic structure of the X-ray CT imaging apparatus which concerns on Embodiment 2 of this invention.

Explanation of symbols

1 imaging system 2 X-ray tube 3 X-ray detector 4 subject 6 subject's body axis 7 grid

Claims (2)

An imaging system consisting of a radiation tube that irradiates the subject with radiation and a two-dimensional radiation detector that detects the radiation that has passed through the subject is placed oppositely across the subject, and the imaging system is rotated toward the subject while being integrally rotated. In the radiation imaging apparatus for irradiating radiation and detecting the radiation projection image of the subject with the radiation detector,
A grid is disposed in a cylindrical shape so as to surround the body axis of the subject, the radiation tube is disposed in a space between the subject and the grid, and the radiation detector is disposed in a space outside the grid disposed in a tubular shape. A radiographic apparatus characterized by being arranged.   The radiation imaging apparatus according to claim 1, further comprising a guide member that moves at least one of the grid and the imaging system in a body axis direction of a subject.

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