JPH038246Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a holding mechanism for a grid disposed on a film of a multi-orbit tomography apparatus.

In general, multi-orbit tomography equipment selectively moves the X-ray tube focal point and film surface relative to each other across the subject, not only in a straight line but also in a variety of trajectories such as circles, ellipses, and spirals. Furthermore, there are many devices in use in which the subject can be arbitrarily changed not only from a horizontal position but also from a standing position to a reverse oblique position. When performing the above-mentioned circular, elliptical, or spiral trajectory in such an apparatus, the amount of X-ray information is cut and In order to eliminate off-loss and increase the amount of X-ray information that reaches the film, the direction of the lead foil in the grid (hereinafter referred to as the grid direction) must be adjusted to the X-ray tube focal point, that is, the X-ray direction, as the X-ray tube moves. It is necessary to rotate the grid so that it is oriented in the direction of illumination. This rotation is called heliotropic rotation, and for example,
"Multi-orbital tomography device" announced in the issue
There is a device using a planetary gear device as shown in FIG. 1, which will be briefly explained with reference to FIG. X _O
is the X-ray focus at the vertical position, F _O indicates the imaging center at that time, the linear trajectory R _XS of the X-ray focus is X _A X _E including the above X _O , and the corresponding imaging center is F The straight line trajectory R _FS of _A F _O F _E becomes. As shown in the figure, the grid G on this locus R _FS has the grid direction (arrow C) coincident with the locus R _FS . Next, the circular orbit of the X-ray focal point _XA is indicated by the dashed line.
When moving R _X counterclockwise (arrow a),
For example, when moving by an angle of θ and arriving at X _B , the radiation cone axis X C is the tomographic center O of the subject (not shown).
Move by the same θ angle around . That is, the imaging center F _A rotates on a circular locus R _F indicated by a two-dot chain line. Although not shown, grid G when F _A
As mentioned above, is the grid direction (arrow C), but in other words, the grid is aligned with the direction of the X- _ray radiation cone axis X・_C '. The above-mentioned heliotropic rotational movement is the rotation. Therefore, the center of grid G is the circular locus R _F
For example, when it rotates once and returns to F _A and enters the above linear orbital motion, the above lattice direction c is F _E −F _O −
Since this coincides with F _O F _A , the lattice GL is swung in a direction perpendicular to the lattice direction C (arrow (h)) to prevent stripes of the lattice G _L from appearing on the photograph. In this way, the grid of a multi-orbit tomography apparatus must be selectively driven to perform two types of motion: oscillation during a straight orbit, and heliotropic rotation during a circular or elliptical orbit. The grid holding mechanism conventionally used in this type of device is, for example, a ring-shaped grid having approximately the same diameter as the round hole and teeth cut around the entire periphery on a substrate having a round hole opening for the X-ray emitting cone in the center. The rotary member is rotatably supported, and a circular focusing grid is supported in the inner hole of the rotary member at two points on the periphery corresponding to the swinging direction by two leaf springs. Therefore, the heliotropic rotational movement of the grid can be achieved either by a mechanical transmission in which a pinion meshing with teeth around the entire circumference of the rotating member is driven by the aforementioned planetary gear system;
Alternatively, it may be rotated by synchronized electric transmission. Further, the rocking motion during the linear trajectory is caused by a swing lever provided on the base plate and driven by a solenoid, which applies an impact in the rocking direction of the grid to cause the grid to swing. However, with the above-mentioned conventional grid holding mechanism, the grid must be rotated when performing circular orbit tomography in a standing position, for example, in a tabletop raising/lowering device in which the top plate on which the subject is placed is raised and folded as described above. Not,
As the grid rotates and the direction connecting the two points supported by the leaf spring approaches the center of gravity of the grid, the leaf spring bends due to the grid's own weight.
There is a drawback that the focus of the grid is misaligned with respect to the focus of the X-ray, resulting in a decrease in image quality.

This idea was made in view of the above-mentioned current situation, and even in multi-orbit tomography equipment equipped with at least a straight or circular orbit, especially in the tilting top type, the rotation of the grid causes the rotation of the grid regardless of the direction of the center of gravity. The object is to provide a holding mechanism that does not cause positional displacement.

That is, a swinging trajectory is formed on a grid holding mechanism board that moves relative to the X-ray tube, and a plurality of swinging plate members attached to the swinging plate member are mounted on the grid holding mechanism board. A guide roller is engaged with the swing track and held so as to swing a predetermined distance in a direction perpendicular to the radiation cone axis direction of the X-ray tube by the driving force of the swing drive source, and the grid is held. A mask is supported on the rocking orbit formed on the mechanism board, and a grid rotating member is rocked on the rocking plate-like member so as to cause the grid to rotate in a heliotropic manner about the radial cone axis. A pinion, which is rotatably supported and held via a plurality of guide rollers other than the above attached to the moving plate member and meshes with a spur gear formed on the circumferential edge of the grid rotating member, is fixed. a pinion shaft rotatably supported by the rocking plate-like member; a link having one end rotatably engaged with the pinion shaft; and a link rotatably connected to the other end of the link via a pivot shaft. a link different from the above, one end of which is movably connected and the other end rotatably engaged with a rotating shaft of a rotational drive source;
A sprocket fixed to the pinion shaft, a pair of sprockets fixed to the pivot shaft and rotating together, a sprocket fixed to the rotation shaft of the rotational drive source, a sprocket of the pinion shaft and one of the pivots. A rotational driving force transmission mechanism is constituted by each timing belt, which is placed between the sprocket and the other sprocket of the pivot shaft and the sprocket of the rotational shaft of the rotational drive source, and transmits the rotational driving force. The present invention relates to a multi-orbit tomography apparatus characterized in that the grid rotating member is rotated by a rotational drive source via a mechanism.

Embodiments of this invention will be described below with reference to the drawings. Fig. 2 is a front view of the grid holding mechanism 15 of the multi-orbit tomography apparatus of this invention, Fig. 3 is a side view thereof, the right half is a sectional view taken along the line -' in Fig. 2, and Fig. 4 is a right side view thereof. The right half is a sectional view taken along the line -' in FIG. F indicated by a two-dot chain line in Fig. 3 is an X-ray film, and its center point F _O is always located coaxially with the center point G _O of the grid in Fig. 2 and the X-ray radiation cone axis X C. It is configured as follows. The film cassette and other mechanisms are not shown.
The grid holding mechanism base plate 16 has an opening 16H for the X-ray radiation cone X and, during linear trajectory movement, extends in the direction h perpendicular to the grating direction c (only a portion of which is shown) of the focal grid G, for example ±. A constant speed motor 18 that drives the 10 mm oscillating motion and a servo motor 19 that drives the heliotropic rotational motion of the grid G.
and is fixed. The substrate 16 is
The focusing grid G is configured to move relative to the X-ray tube so that the focal point of the focusing grid G always coincides with the focal point of the ray tube (not shown), but their configuration is the same as that of the conventional apparatus. Next, there are swing tracks 20A and 20B installed in parallel on this board 16.
Side surfaces 20S of a constant width at both ends of the top are formed in an arc shape, and are rotatably mounted on four first support shafts 22 provided on a swinging plate-like member 21 (hereinafter referred to as swinging plate). It is swingably engaged with the supported first guide roller 23. These four guide rollers 2
3 of the rocking plate 21, and the rocking plate 21 is swingably supported at
A convex portion 24 is provided on the base plate 16, and tension springs 26, 26' stretched between the convex portion 24 and two pins 25, 25' arranged on the substrate 16 keep the rocking plate 2
Since the position of 1 is regulated, unlike the leaf spring supported type of conventional equipment, depending on whether the top plate is tilted in the longitudinal direction (arrow P) or on the P' side, the grid can be fixed regardless of the rotation of the grid G. One of the main features of this invention is that it can completely prevent misalignment due to its own weight. A long hole 27 is bored in the right shoulder of the rocking plate 21, and an eccentric plate 29 that eccentrically supports a small-diameter ball bearing 28 that fits into the hole 27 is driven by the constant speed motor 18 to a predetermined position. By rotating at the rotation speed, the lattice spacing of the grid can be reduced to 0.35 mm, for example.
(grid ratio 1/8), approximately 130mm/
The grid G is oscillated at a moving speed suitable for erasing the grid pattern, such as sec. The X-ray aperture of this swing plate 21 is 21H. Next, on this rocking plate 21, the same 4
A second shaft rotatably supported on the second support shaft 30 of the book.
The guide roller 31 supports the lower peripheral edge 33 of the grid rotating member 32 at four points. Furthermore, a spur gear 32T is provided around the entire upper periphery of the grid rotating member 32.
The pinion 34 that meshes with this pinion shaft 35 is rotatably supported on the rocking plate 21 by a bearing 36, and a sprocket is attached coaxially to the pinion 34, as shown in the cross section of FIG. A37 is fixed, and a link A38 is also engaged below it via a bearing 39. The other end of the link A38 is connected to the link B41 via the pivot 40.
The pivot shaft 40 is rotatably connected to the sprocket B42, which corresponds to the sprocket A37.
It rotatably supports another sprocket C43 which rotates coaxially with the sprocket. Sprocket A3
7. A timing belt A44 is stretched over B42, and a sprocket D45, which also corresponds to sprocket C43, is connected to the rotation shaft 4 of the servo motor 19.
6, and the timing belt B
47 is stretched between the two sprockets. The above link B41 also has a bearing (not shown)
It is rotatably supported by the motor rotation shaft 46 via the motor rotation shaft 46 . With this configuration, the grid rotating member 3
Even during the swinging in the n direction of the servo motor 19
The rotation of is transmitted to the pinion 34,
The grid rotation member 32 is rotated by the rotation of the grid rotation member 32. Mask 4 for adjusting the irradiation field directly below Grid G
8, 48' are slidably supported on the swing tracks 20A, 20B, but the masks 48, 48'
Since it is not directly related to this idea, a detailed explanation will be omitted. Fifth
The figure is a block diagram showing a drive circuit for heliotropic rotation of the servo motor 19. The rotational position of the X-ray tube focus explained in FIG. 1 is detected by a combination of a synchro transmitter 51 and a synchro receiver 52. The detection signal is amplified by the servo amplifier 54 via the changeover switch 53 and applied to the servo motor 19, thereby imparting the above-mentioned heliotropic rotational motion to the grid G. Furthermore, if the starting point of the X-ray focal point is, for example, X _A in Fig. 1, it is necessary to always return the X-ray tube focal point to X _A at the start of imaging. Therefore, by switching the switch 53 to the contact 53S, the origin position is set. The servo motor 19 is rotated by a signal preset in the controller 55, and the grid rotating member 3 is rotated.
2 and return its center point G _O to the position of F _A in Figure 1, and at the same time make the lattice direction C coincide with the linear trajectory R _FS .

Although the above is one embodiment of the device of this invention, this invention is not limited to the illustrations and description. For example, the heliotropic rotational movement of the grid is not limited to being electrical, but may also be mechanical using a planetary gear system. Further, the grid may be other than the focal grid, and the swing drive may be a constant distance reciprocating drive system consisting of a wire stretched between the motor shaft and a pulley, and two microswitches, instead of the eccentric plate described above. In addition, although the explanation was given using a straight orbit and a circular orbit, the same operation occurs when using an elliptical orbit or a spiral orbit.

Since this invention is constructed as described above, even when the top plate of the multi-orbit tomography apparatus is raised and lowered, there is no displacement of the grid position due to gravity.
Since the focal point of the mainly used focal grid always coincides with the X-ray focal point, it not only prevents cut-off loss of X-ray information and improves image quality, but also improves the image quality of the grid during straight trajectory. The oscillation speed can be set appropriately, the grid effect is improved, and high-quality images without streaks can be obtained, and the entire grid can be made thinner than conventional grid holding mechanisms by incorporating a mask. is possible,
This provides a convenient device that allows the subject to be brought closer to the film, reduces the magnification of the photograph, and provides sharper image quality.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram explaining the heliotropic rotational movement of the grid of a multi-orbit tomography apparatus, Fig. 2 is a front view of the grid holding mechanism of the embodiment of the multi-orbit tomography apparatus according to this invention, and Fig. 3 is the side of the above mechanism (1
4 is a right side (partial sectional) view of the above mechanism, and FIG. 5 is a block diagram of the solar tropism rotation drive circuit of the above mechanism. R _XS ... linear trajectory _{of the} X _- ray tube, R Radial cone of tube,
... Swinging direction, 21... Swinging member, 31... Guide roller pivotally supported on swinging member 21, 32... Grid rotating member, G _O ... Rotation center of grid G.

Claims (1)

[Scope of utility model registration request] The X-ray tube and the film are moved relative to each other at least in a straight line or in a circular orbit across the object, and a grid for removing scattered radiation arranged on the film is subjected to linear rocking or heliotropic rotation. In a multi-orbit tomography apparatus that imparts motion to image the subject, a swing trajectory is formed on a grid holding mechanism board that moves relative to the X-ray tube, and a swinging trajectory is formed on the grid holding mechanism board that moves relative to the X-ray tube. The plate-like member is moved by a plurality of guide rollers attached to the swinging plate-like member.
The grid holding mechanism is held so as to be engaged with the swing track and swing a predetermined distance in a direction orthogonal to the direction of the radiation cone axis of the X-ray tube by the driving force of the swing drive source, and the grid holding mechanism The mask is supported on the rocking orbit formed on the substrate, and the grid rotating member is mounted on the rocking plate-like member, and the rocking plate is configured to cause the grid to rotate in a heliotropic manner about the radial cone axis. A pinion that is rotatably supported and held via a plurality of guide rollers other than those attached to the grid member and meshes with a spur gear formed on the circumferential edge of the grid rotating member is fixed. a pinion shaft rotatably supported by the rocking plate-like member; a link having one end rotatably engaged with the pinion shaft; and a link rotatably connected to the other end of the link via a pivot shaft. a link different from the above, one end of which is movably connected and the other end rotatably engaged with a rotating shaft of a rotational drive source, a sprocket fixed to the pinion shaft, and a sprocket attached to the pivot shaft. , a pair of sprockets that rotate together, a sprocket fixed to the rotating shaft of the rotational drive source, a sprocket of the pinion shaft and one sprocket of the pivot shaft, and a sprocket between the other sprocket of the pivot shaft and the rotational drive. A rotational driving force transmission mechanism is constructed from each timing belt that is respectively suspended between the sprocket of the rotating shaft of the source, and the rotational driving source rotates the grid rotating member through the rotational driving force transmission mechanism. A multi-orbital tomography device characterized by: