JPH05115471A - X-ray ct system - Google Patents

Abstract

PURPOSE:To provide the X-ray CT system which can improve the picture quality of a photographing image by reducing a body motion of a body to be examined at the time of helical scan. CONSTITUTION:In the X-ray CT device 1 which is provided with a rack table 3 on which an X-ray tube 4 for radiating X rays to a body P to be examined is provided so as to be rotatable and executes a helical scan by which a relative locus to the body P to be examined of the X-ray tube 4 becomes a spiral shape at the time of photographing, a rack table driving mechanism 16 for driving the rack table 3 is provided, and at the time of helical scan, the helical scan is executed by allowing a bed top plate 2A on which the body P to be examined is placed to stand still, and also, driving the rack table 3 by the rack table driving mechanism 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus for creating a tomographic image of a subject based on information on the X-ray absorption coefficient obtained by scanning the subject with X-rays.
In particular, it relates to an X-ray CT apparatus that performs a helical scan.

[0002]

2. Description of the Related Art Conventionally, there is an X-ray CT apparatus of this type as shown in FIG. 7, for example. In the figure, the X-ray CT apparatus 100 includes a bed 101 and a gantry 102 having an imaging hole 102A formed in the center. A top plate 101A on which the subject P is placed is provided on the upper part of the bed 101, and the top plate 101A is moved in the arrow direction shown in FIG. Driven. Further, an X-ray tube (not shown) is rotatably provided inside the gantry 102, and at the time of photographing, the X-ray tube rotates around the photographing hole 102A while irradiating X-rays.

When performing a helical scan in the X-ray CT apparatus 100, the top plate 10 on which the subject P is placed is used.
1A is inserted into the photographing hole 102A of the mount, and the top plate 101A
Is moved in the direction of the arrow, the subject P is moved in the body axis direction thereof, and the X-ray tube is moved to the imaging hole 102A.
Continuously rotate around. At this time, for example, when the top plate 101A is driven in the direction of arrow a as shown in FIG. 8, the relative trajectory of the X-ray tube with respect to the subject P has a spiral shape as shown in FIG. By performing such a helical scan, three-dimensional image information of the subject P can be obtained in a short time.

[0004]

However, in the case of the above-mentioned prior art, the top board 10 is in the middle of the helical scan.
Since 1A and the subject P are moved, the subject P being photographed
There is a problem that the image quality of the captured image is poor because the body movement is large, and therefore the artifact is significantly generated due to the body movement. The main cause of this body movement is the top 10 when the top 101A is driven.
This is due to mechanical factors such as bending, vibration, and horizontal movement of 1A and the movement of the subject P in response to the mechanical factors.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to reduce the body movement of the subject during helical scanning and improve the image quality of the picked-up image. It is to provide an X-ray CT apparatus capable of performing the above.

[0006]

In order to achieve the above object, the present invention comprises a gantry on which an X-ray tube for irradiating an object with X-rays is rotatably provided, and at the time of imaging, the X-ray tube is used. In an X-ray CT apparatus that performs a helical scan in which the relative trajectory of the X-ray tube to the subject is a spiral shape, a gantry driving unit that drives the gantry is provided, and at the time of the helical scan, the bed top on which the subject is placed. A helical scan is performed by stopping the plate and driving the gantry by the gantry driving means.

[0007]

In the X-ray CT apparatus of the present invention having the above structure, the gantry is moved by the gantry driving means while rotating the X-ray tube in the gantry, and the gantry is placed on the gantry. With the top plate left stationary,
A helical scan can be performed by moving the X-ray tube so as to draw a spiral shape relative to the subject. Therefore, at the time of helical scanning, the subject is placed on the stationary tabletop, so that body movement due to movement of the tabletop is prevented, and body movement of the subject during imaging is significantly reduced. .. As a result, it is possible to reduce the occurrence of artifacts due to body movements and to improve the quality of captured images.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of an X-ray CT apparatus according to an embodiment of the present invention. As shown in the figure, the X-ray CT apparatus 1 includes a bed 2 and a pedestal 3 in which an imaging hole 3A is formed in the center. A top plate 2A on which the subject P is placed is provided on the upper part of the bed 2, and the top plate 2A is housed inside the bed 2 by the bed drive unit 2B.
Are driven in the vertical direction and the b and c directions. Inside the gantry 3, the X-ray tube 4 for irradiating the subject P with x-rays and the subject P
The detector 5 that detects the X-rays that have passed through is disposed opposite to each other. The X-ray tubes 4 and 5 are attached to a rotating plate (not shown) and are rotatably provided.
X-ray irradiation and X-ray detection are performed while rotating around A.

The X-ray CT apparatus 1 also includes an X-ray tube 4
Image data obtained by the high-voltage generator 6 that supplies a high voltage to the camera, the X-ray controller 7 that controls the high-voltage generator 6, the gantry mechanism controller 8 that controls the movement of the gantry 3 and the top plate 2A, and the detector 5. A data collection unit 9 that collects data, and an image processing unit 1 that reconstructs an image based on these data and performs image processing.
0, a storage unit 11 that stores the obtained image data and the like, a display unit 12 that displays the reconstructed image, a control unit 13 that controls each unit of these devices, and an operator gives instructions to the control unit 13. The operation unit 14 is provided. The control unit 13 includes a CPU 15. The gantry mechanism control unit 8 includes a gantry movement control unit 8A that controls the movement of the gantry 3 described later and a bed control unit 8B that controls the movement of the top 2A.

The apparatus 1 of this embodiment is provided with a gantry driving mechanism 16 as gantry driving means for driving the gantry 3. As shown in FIG. 2, the gantry driving mechanism 16 includes a screw guide 17 attached to the lower center of the gantry 3,
A screw guide support portion 18 indicating both ends of the screw guide 17, two guide rollers 19A and 19B fixed to the lower portions of both side surfaces of the pedestal 3, and fixed to an installation surface such as a floor on which the pedestal 3 is placed. It is provided with two guide rails 20A and 20B arranged and a drive motor 21 (shown in FIG. 1) for rotationally driving the screw guide 17.

The guide rollers 19A and 19B move on the guide rails while being guided by the guide rails 20A and 20B, respectively. As shown in FIG. 3, one of the guide rollers 19A has a bottom surface which is substantially a bottom surface, and a guide rail 20A which abuts the guide roller 19A has a substantially flat surface. .. On the other hand, as shown in FIG. 4, the other guide roller 19B has a recess (groove) whose bottom surface has a substantially triangular cross section, and the guide rail 2 that abuts on this guide roller 19B.
On the upper surface of 0B, there is formed a convex portion shaped to fit into this concave portion.

When performing a helical scan in the X-ray CT apparatus 1 of the present embodiment, first, the table 2A on which the subject P is placed is moved upward by the bed driving unit 2B and the arrow b.
Drive the camera in the direction of the arrow to move the top plate 2A and the subject P to the imaging hole 3 of the mount.
Insert and install in A. At this time, the position of the table 2A is detected by a detection unit (not shown) provided inside the bed 2, and the detection information is sent to the control unit 13 via the bed control unit 8B. The control unit 13 sends a control signal to the gantry movement control unit 8A in accordance with the top plate position information. The gantry movement control unit 8A controls the drive of the drive motor 21 according to this control signal.

When the drive motor 21 rotationally drives the screw guide 17 under the control of the gantry movement control section 8A, the gantry 3
Moves in the direction of arrow b or arrow c, that is, in the body axis direction of the subject P. When the gantry 3 moves, the concave portion of the guide roller 19B described above moves on the guide rail 20B while fitting into the convex portion of the guide rail 20B.
The guide rollers 19A and 19B move on the guide rails without coming off from the guide rails 20A and 20B. As a result, the pedestal 3 becomes the guide rail 2
Move on a straight line along 0A and 20B. At the same time, the X-ray tube 4 and the detector 5 in the gantry 3 rotate around the imaging hole 3A and perform X-ray irradiation and X-ray detection on the subject P. At this time, the relative trajectory of the X-ray tube 4 with respect to the subject P has a spiral shape. After performing the helical scan in this manner, the bed driving unit 2B drives the top plate 2A.
1 is driven in the direction of arrow c shown in FIG. 1 to return it to its original position, and the top plate 2A is further driven downward to be placed at an appropriate height, and then the subject P is lowered from the top plate 2A.

In the present embodiment, as described above, with the top plate 2A on which the subject P is placed kept stationary,
A helical scan can be performed by moving the X-ray tube 4 relative to the subject P so as to draw a spiral shape.
Therefore, at the time of helical scanning, the subject P is placed on the stationary top plate 2A, so that the body movement of the subject P during imaging is significantly reduced. As a result, it is possible to reduce the occurrence of artifacts due to body movement, improve the resolution and resolution of images, and improve the quality of captured images.

Further, when the top plate 2A on which the subject P is placed is moved, the subject P is burdened with pain and discomfort due to vibration of the top plate 2A. In the case of the present embodiment. In addition, since the subject P is stationary during the helical scan, such a burden on the subject P can be reduced. Furthermore, since the subject P is stationary during imaging, it is easy to handle a medical device such as a drip device in contact with the subject P.

FIG. 5 is a perspective view showing a part of an X-ray CT apparatus according to another embodiment of the present invention. In the figure, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, instead of the gantry driving mechanism 16 using the screw guide 17, a gantry driving mechanism 26 driven by a chain is provided. The gantry drive mechanism 26 includes a drive motor 27, a speed reducer 28 connected to the drive motor 27, a sprocket 29, and a chain 3 wound around the sprocket 29.
0, guide rollers 19A and 19B and guide rails 20A and 20B attached to the lower portions of both side surfaces of the gantry 3.

The chain 30 is doubled and passes through the lower portion of the pedestal 3, one end side of which is wound around the sprocket 29 as described above, and the other end side of the sprocket 29 with the pedestal 3 interposed therebetween. Is wound around a support member such as a pulley (not shown) on the opposite side. Further, of the two chain portions that pass through the lower portion of the pedestal 3, only one chain portion is fixed to the lower portion of the pedestal 3. The other components are the same as those in the above embodiment shown in FIG.

When performing a helical scan in this embodiment, the drive motor 27 rotationally drives the chain 30 via the speed reducer 28 and the sprocket 29, so that the gantry 3 moves together with the fixed chain portion. .. That is, also in this embodiment, similarly to the above-described embodiments, the X-ray tube is moved by moving the gantry 3 in the body axis direction of the subject while the top plate on which the subject is placed is kept stationary. Helical scan can be performed by moving 4 so as to draw a spiral shape relative to the subject. Therefore, it is possible to obtain the same effect as that of the above embodiment.

FIG. 6 shows an X-ray C according to still another embodiment of the present invention.
It is a side view which shows a part of T device. In this embodiment, there is provided a top plate support portion 40 that supports the tip end portion of the top plate 42A of the bed 42 on which the subject P is placed, and a part of the gantry drive mechanism 46 is part of the top plate support portion 40. It is located inside the lower part. The gantry drive mechanism 46 is a chain drive mechanism similar to the gantry drive mechanism 26 of the above embodiment shown in FIG. The drive unit 46A including the drive motor, speed reducer, and sprocket of the gantry drive mechanism 46 is the top plate support unit 40.
Stored inside the. In FIG. 6, 46B indicates a supporting member such as a pulley around which the chain 50 is wound.
The other components are the same as those in the above-described embodiment shown in FIG. 1 or FIG.

During the helical scan, the top plate 42A on which the subject P is placed is driven in the direction of the arrow d, and the top plate 42A is projected from the bed 42, and the tip of the top plate 42 is placed on the top plate support portion 40. Placed on. That is, since both ends of the top plate 42A are supported by the bed 42 and the top plate support portion 40, even if the top plate 42A is largely projected from the bed 42,
The subject P and the top plate 42 are reliably supported in a stable state. After this, the gantry 43 is driven in the direction of arrow e, that is, the body axis direction of the subject P, and a helical scan is performed.
In the case of this embodiment, as compared with the embodiment shown in FIG. 1, the subject P is supported in a more stable state by using the top plate supporting portion 40, so that the body movement of the subject during the helical scan. Can be further reduced. In this embodiment, a drive mechanism using a screw guide as shown in FIG. 2 may be provided instead of the gantry drive mechanism 46 driven by the chain.

The embodiment of the present invention has been described above.
The present invention is not limited to this, and various modifications can be made. For example, in the above embodiment, the case where the gantry is driven along the guide rail provided on the installation surface below the gantry has been taken as an example, but it is also possible to drive the gantry along the ceiling hanging guide.

[0023]

The X-ray CT apparatus of the present invention having the above-described configuration and operation can reduce the body movement of the subject during helical scanning, and as a result, reduce the occurrence of artifacts due to the body movement. However, the quality of the captured image can be improved. Further, it is possible to reduce the burden on the subject due to the movement of the bed top.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a part of the apparatus of the embodiment.

FIG. 3 is a cross-sectional view showing one guide roller and one guide rail in the embodiment.

FIG. 4 is a cross-sectional view showing the other guide roller and guide rail in the embodiment.

FIG. 5 is a perspective view showing a part of an X-ray CT apparatus according to another embodiment of the present invention.

FIG. 6 is a side view showing a part of an X-ray CT apparatus according to still another embodiment of the present invention.

FIG. 7 is a perspective view showing a part of a conventional X-ray CT apparatus.

FIG. 8 is an explanatory diagram for explaining a helical scan in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray CT apparatus 2 Bed 2A Top plate 3 Frame 4 X-ray tube 5 Detector 8 Frame mechanism control unit 13 Controller 16 Frame driving mechanism (frame driving means) 17 Screw guide 18 Screw guide support 19A, 19B Guide roller 20A , 20B guide rail 21 Drive motor

Claims (1)

[Claims] 1. A helical scan is provided, wherein a gantry on which an X-ray tube for irradiating an X-ray to a subject is rotatably provided, and at the time of imaging, a helical scan is performed so that the relative trajectory of the X-ray tube with respect to the subject becomes a spiral shape. In the X-ray CT apparatus, a gantry driving means for driving the gantry is provided, and at the time of a helical scan, the bed top plate on which the subject is placed is made stationary, and the gantry driving means drives the gantry to make a helical mount. An X-ray CT apparatus characterized by scanning.