JPH0471535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to improvement of an X-ray multi-orbit tomography apparatus.

(b) Prior Art In X-ray photography, it is known that if an X-ray grid 2 is placed on a film 1 as shown in FIG. 1, an effect of removing scattered radiation can be obtained by this X-ray grid 2. On the other hand, in the X-ray multi-orbit tomography apparatus, the X-ray focal point of the X-ray tube device 3 and the lead foil of the X-ray grid 2 must have a heliotropic relative relationship with each other. That is, when the X-ray tube device 3 moves on a straight trajectory as shown in FIG. 1, the direction of the X-ray grid 2 is determined so that the linear trajectory is parallel to the lead foil, and When moving on a circular orbit as shown in
It is necessary to rotate the line grid 2. If such a heliotropic relative relationship is not maintained, cut-off of the X-rays by the lead foil of the X-ray grid 2 will occur. This means that not only an excessive amount of X-rays is required, but also inconveniences such as a decrease in the contrast of the X-ray photograph are caused.

However, with conventional X-ray multi-orbit tomography equipment,
There was a problem that the direction of the heliotropic movement of this X-ray grid was unreliable and had low accuracy.

(c) Purpose This invention enables the creation of various trajectories such as straight lines, circles, ellipses, and spirals with a simple and compact mechanism, and enables highly accurate heliotropic movement of the X-ray grid. An object of the present invention is to provide an X-ray multi-orbit tomography apparatus which improves the image quality of X-ray tomography and reduces the X-ray exposure dose.

(d) Configuration The X-ray multi-orbit tomography apparatus of the present invention includes a main rotary disk rotatably held on a substrate, a sub-rotary disk rotatably attached to the rotation center of the main rotary disk, and a sub-rotary disk rotatably attached to the rotation center of the main rotary disk. A rotary lever is rotatably attached to a location other than the center of rotation of the rotary disk, is connected to the sub-rotary disk, and is rotated by the sub-rotary disk. The rotary disk is rotatably driven by a reducer with a changeable reduction ratio connected to the rotary drive device via a clutch, and its rotation can be stopped by a brake. - By turning the clutch on and off, the main rotary disk and the sub-rotary disk are rotated in relation to each other, and by combining these two rotational movements, the tip of the rotary lever can be moved in a straight line, in a circle,
Since it is possible to draw various trajectories such as an ellipse or a spiral, the X-ray tube device is moved following the movement of the tip of this rotary lever. When such a mechanism is adopted, focusing on the fact that the direction of the X-ray focal point has a correlation with the direction of the sub-rotary disk, the movement of the sub-rotary disk in the rotational direction is measured on the imaging means. X is held rotatably by
The X-ray grid is transmitted to the X-ray grid, and the X-ray grid is rotated in accordance with the rotation of the auxiliary rotary disk, so that a heliotropic movement of the X-ray grid is performed.

(E) Embodiment In FIG. 3, the main frame 10 has a substrate 11 above and a base 12 below. A main rotary disk 20 is rotatably held on the base plate 11. A sub-rotary disk 30 is rotatably held at the center of rotation of the main rotary disk 20, and a rotary lever 40 is rotatably located at a position off the center of rotation. attached. This sub-rotary disk 30 has a gear 31 and a pulley 32, and the gear 3
1 is engaged with gear 41 of rotary lever 40 via idle gear 33. A shaft 42 is rotatably attached to the tip of the rotary lever 40,
This shaft 42 is connected to a bearing 43. This bearing 43 has a holding shaft 44 that holds the X-ray tube device 3.
Although it is rotatable, it is mounted so that it cannot move in the axial direction.

As shown in FIG. 4, the main rotary disk 20 is rotatably driven by a pulley 22 via a belt 21, and this pulley 22 is rotated by a drive motor 23 via a belt-pulley mechanism. It is connected to the output shaft of the speed reducer 24 to which force is applied. The other output shaft 25 of this reducer 24 is connected to the input shaft of a reducer 27 via a clutch 26.
The output shaft of this reducer 27 is connected to a pulley 28. This pulley 28 rotationally drives a pulley 32 of the sub-rotary disk 30 via a belt 34. The belt 34 is also passed around the pulley 35,
This pulley 35 is connected to a gear 36, and the gear 36 meshes with a gear 37 connected to a rotating shaft 38. The rotating shaft 38 is configured to be stopped from rotating by a brake 39.

In this way, by turning on and off the clutch 26, varying the reduction ratio of the reducer 27, and operating the brake 39, the main rotary disk 20 and the sub-rotary disk 30 can be rotated independently, or they can be correlated to each other at a constant ratio. It is now possible to rotate both at a speed of . Here, it is assumed that the position of the rotation center of the rotary lever 40 is located at a distance R from the rotation center 0 of the main rotary disk 20, the distance from the rotation center of the rotary lever 40 to the rotation shaft 42 is also R, and the gear 31
The rotation ratio between the gear 41 and the gear 41 is 1:2, and assuming that the first position X1 of the rotating shaft 42 coincides with point 0, the clutch 26 is turned off and the brake 3 is turned off.
9 is operated to stop the rotation of the sub rotary disk 30 and only the main rotary disk 20 is rotated, the position of the rotating shaft 42 moves on a straight line passing through point 0. That is,
Assuming that the main rotary disk 20 rotates by an angle θ, the gear 41 moves from the solid line position to the two-dot chain line position in FIG. The position X2 is 2R sin θ in the X direction of FIG. 4, and is always 0 in the Y direction. In other words, as the main rotary disk 20 continues to rotate, the position X2 will reciprocate on a straight line of length 4R extending in the direction of the specific diameter PQ of the stopped sub-rotary disk 30.

After rotating the main rotary disk 20 by a predetermined angle, the brake 39 is released and the clutch 2 is simultaneously
6 are connected and the sub-rotary disk 30 is rotated simultaneously with the rotation of the main rotary disk 20. If the rotational speeds are the same, the position X2 of the shaft 42 at the tip of the rotary lever 40 will draw a circular trajectory, and both If the rotational speed of is different, it will draw a spiral trajectory. In this case, regardless of whether the orbit is circular or spiral, the position X2 of the shaft 42 will always be on the extension of the specific diameter PQ of the sub-rotary disk 30.

When the rotating shaft 42 moves on various trajectories as described above, the X-ray tube device 3 follows and moves to draw the same trajectory. As the X-ray tube device 3 moves, the film 1 held in the imaging frame 60 is symmetrically moved around the center point on the tomographic plane 6 of the subject 5. is starting to move. That is, the X-ray tube device 3 is rotatably attached to the tip of a holding shaft 44 with a pin 45, and the other end of this holding shaft 44 is rotatably attached to one end of a connecting lever 47 with a pin 46. There is. The frame 48 is attached to the collimator 4 fixed to the X-ray tube device 3 and the connecting lever 47 with rotatable pins 49 and 50 to form a parallelogram link, and the X-ray tube device 3 is moved. Even in this case, the collimator 4 is directed toward the subject 5. The connecting lever 47 has a spline bearing 5
1, it does not rotate but is held movable in the axial direction, and this bearing 51 is held by a pin 52.
It is rotatably supported by a U-shaped member 53, and this U-shaped member 53 itself is rotatably held on the side wall portion of the main frame 10 by a rotating shaft 54. The fulcrum of the connecting lever 47, that is, the position where the pin 52 and the shaft 54 intersect corresponds to the tomographic plane 6. This connecting lever 4
A spline bearing 55 is attached to the other end of the frame 7 so as to be movable in the axial direction without rotating, and this bearing 55 is attached to an extension 61 of the imaging frame 60 so as to be able to freely precess. Imaging frame 60
has wheels 62, and these wheels 62 are placed on rails 64 provided on a moving frame 63, so that the wheels 62 can be moved in the left-right direction in the figure. Further, the wheels 65 of the moving frame 63 are placed on rails 66 provided on the base 12, so that the moving frame 63 can move in a direction perpendicular to the plane of the paper. In this way, the imaging frame 60 is freely moved two-dimensionally on the base 12 as the lower end side of the connection lever 47 moves.

A disk-shaped grid frame 70 that rotatably holds the X-ray grid 2 is provided above the imaging frame 60 and between it and the bed top plate 7 on which the subject 5 is placed. A gear is formed in the image pickup frame 60, and this gear meshes with a gear 71 connected to a rotating shaft 72 attached to one end of the imaging frame 60. One end of a lever 73 is rotatably attached to this rotating shaft 72, and the other end of this lever 73 is attached to one end of a lever 75 via a rotating shaft 74. The other end of the lever 75 is rotatably attached to the rotation shaft 38 mentioned above. Further, the rotation of the rotating shaft 38 is controlled by a pulley 76 fixed to the rotating shaft 38 and a belt 7.
7. The signal is transmitted to a pulley 81 attached to the rotating shaft 72 via the rotating shaft 74, the pulley 79, and the belt 80. In this way, the rotational movement of the sub-rotary disk 30 is transmitted as the rotational movement of the grid frame 70 on a 1:1 basis.

Therefore, the X-ray grid 2 rotates in a direction corresponding to the specific diameter PQ of the sub-rotary disk 30. By the way, the specific diameter of the sub-turntable 30
As mentioned above, the rotation axis 42 is located in the direction of PQ, but the position of the X-ray tube device 3 is on this rotation axis 42.
2, it is possible to achieve highly accurate heliotropic movement of the X-ray grid 2 with respect to the X-ray tube device 3.

The functions of the levers 73, 75, belts 77, 80, and pulleys 76, 78, 79, 81 are such that no matter how the imaging frame 60 moves, they follow it and move as shown in FIG. The objective is to transmit only the rotation of 38 to the rotating shaft 72.

In each of the above parts, rotation is transmitted using a belt/pulley mechanism, but a chain/pulley mechanism is used to transmit rotation.
Of course, a sprocket mechanism or other rotation transmission mechanism can be used.

(f) Effect In the X-ray multi-orbital tomography apparatus of the present invention, the main rotary disk is rotationally driven by a rotational drive device, and the auxiliary rotary disk is connected to the rotational drive device via a clutch and has a variable reduction ratio. Since the speed reducer is used to drive rotation, and the brake is used to stop the rotation, the brake can be turned on and off, the clutch can be turned on and off, and the speed reduction ratio can be changed in any combination. In addition to being able to easily create various trajectories,
Mechanically, it is simple and can be made compact. Moreover, by focusing on the fact that the direction of the X-ray focal point is correlated with the direction of the sub-rotary disk necessary for rotational movement, the movement of this sub-rotary disk in the rotational direction can be held freely on the imaging means. The X-ray grid is rotated in accordance with the rotation of the auxiliary rotary disk, and the X-ray grid is made to move in a heliotropic manner. A highly heliotropic movement can be achieved. Therefore, it is possible to reduce the X-ray exposure dose and obtain an excellent X-ray tomogram with good image quality and good contrast.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams for explaining the heliotropic movement of the X-ray grid in an X-ray multi-orbit tomography device, and FIG. 3 is a side view partially showing an embodiment of the present invention. 4 is a schematic plan view of the same embodiment, and FIG. 5 is a schematic plan view of a part of the rotation transmission mechanism for the heliotropic motion of the same embodiment. 1...Film, 2...X-ray grid, 3...
X-ray tube device, 4... collimator, 5... subject,
6...Fault plane, 7...Bed top plate, 10...Main frame, 11...Substrate, 12...Base, 20...
Main rotary disk, 23... Drive motor, 30... Sub-rotary disk, 40... Rotating lever, 60... Imaging frame, 70... Grid frame.

Claims (1)

[Claims] 1. The X-ray tube device and the imaging means are placed opposite to each other with the subject in between, and the In an X-ray multi-orbit tomography system in which the ray tube device is moved on various types of orbits, there is a main rotary disk that is rotatably held on a board, and a rotatably attached to the rotation center of this main rotary disk. a rotary drive device for rotationally driving the main rotary disk; a clutch connected to the output shaft of the rotary drive device; a reducer for rotationally driving the rotary disk; a brake for stopping the rotation of the auxiliary rotary disk; and a brake for stopping the rotation of the auxiliary rotary disk; a rotary lever that is rotated by a rotary lever and transmits the position of its tip to the X-ray tube device to move the X-ray tube device; an X-ray grid that is rotatably held on the imaging means; An X-ray multi-orbit tomography apparatus comprising: a rotation transmission mechanism that transmits motion in a rotational direction to the X-ray grid at the same ratio to rotate the X-ray grid in accordance with the rotation of the sub-rotary disk.