JP2002034966A - X-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus allowing easy and accurate width adjustment and position adjustment to a slit in a collimator, and simplification and formed miniaturization of structure. SOLUTION: An X-ray radiated from an X-ray radiation apparatus to pass a subject is introduced through a slit 9 in a collimator 10 to a detector. The collimator 10 comprises a pair of X-ray shielding members 11 facing each other through a space composing the slit 9, and a slit width adjusting means. The shielding members 11 and the slit width adjusting means are integrally displaceable in a width direction of the slit 9. The slit width adjusting means displaces the shielding members 11 in the width direction of the slit 9 in such a way that their center position in the width direction of the slit 9 is not changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an X-ray CT apparatus.

[0002]

2. Description of the Related Art X-ray CT
The apparatus is provided with an X provided on a rotating frame attached to a fixed frame.
A tomographic image is created by irradiating a subject sent into a rotating rotating frame with X-rays from the irradiation device, and detecting X-rays transmitted through the subject with a detector. Collect data for use. A collimator located between the subject and the detector is arranged on the rotating frame.
The collimator has two blade-shaped X-ray shielding members facing each other via a space forming a slit, and an X-ray passing through the slit is detected by a detector. The width of the slit becomes the slice thickness in tomography.

[0003] Conventionally, in order to adjust the width and position of the slit, a driving device is provided at both ends of each of the two blades, and both blades are individually driven. However, when the two blades are individually driven, the position and width of the slit cannot be individually adjusted, so that the control of the driving device for the adjustment is complicated. Further, a drive device for each of the two blades is required, which complicates the structure and increases the installation space.

In addition, a shim is interposed between the two blades, and both blades are mounted as a unit on a rotating frame via a shim, and the position of the slit is adjusted by changing the mounting position of the unit. Has also been done. However, when adjusting the slit between the two blades as a unit and the mounting position on the rotating frame,
Since it is necessary to adjust the thickness of the shim interposed between the unit and the rotating frame, it is necessary to repeatedly tighten and loosen the bolts and the like that attach the unit to the rotating frame, which requires time and effort. .

[0005] An object of the present invention is to provide an X-ray CT apparatus capable of solving the above problem.

[0006]

According to the present invention, there is provided an X-ray CT apparatus for guiding an X-ray irradiated from an X-ray irradiation apparatus and transmitted through a subject to a detector through a slit of a collimator.
The collimator has a pair of X-ray shielding members facing each other via a space constituting the slit, and slit width adjusting means for displacing both shielding members so that the width of the slit changes. The member and the slit width adjusting means are integrally displaceable in the width direction of the slit, and the slit width adjusting means slits both shielding members so that the center position in the width direction of the slit does not change. In the width direction. According to the configuration of the present invention, even when both shielding members are displaced when adjusting the width of the slit by the slit width adjusting means, the center position in the width direction of the slit does not change. It does not affect position.
Further, the position of the slit can be adjusted by displacing the two shielding members and the slit width adjusting means in the width direction of the slit. At this time, since both the shield members and the slit width adjusting means are displaced integrally, the position adjustment of the slit does not affect the width of the slit. Thereby, the width adjustment and the position adjustment of the slit can be performed individually without affecting each other. When both the shielding members are driven by the driving device, the control can be easily performed, and the two shielding members are individually driven. Since there is no need, the structure can be simplified and downsized.

The slit width adjusting means has a cam which comes into contact with both shield members via a cam follower, and both shield members can be displaced in the width direction of the slit such that the width of the slit changes by the operation of the cam. It is preferable that the shape of the cam is determined so that the center position in the width direction of the slit does not change even when both shielding members are displaced by the operation of the cam. Thus, the width of the slit can be adjusted by displacing the two shielding members only by operating the cam. At this time, even if both the shielding members are displaced by the operation of the cam, the center position in the width direction of the slit does not change, so that the width adjustment of the slit does not affect the position of the slit. Further, the position of the slit can be adjusted by displacing the two shielding members and the cam in the width direction of the slit. At this time, since both the shielding members and the cam are displaced integrally, the position adjustment of the slit does not affect the width of the slit. Thereby, the width adjustment and the position adjustment of the slit can be performed individually without affecting each other. When both the shielding members are driven by the driving device, the control can be easily performed, and the two shielding members are individually driven. Since there is no need, the structure can be simplified and downsized. It is preferable that a driving device for operating the cam is provided, and the driving device is displaceable in the width direction of the slit integrally with the two shielding members and the slit width adjusting means. As a result, when adjusting the position of the slit, the driving device for operating the cam is displaced integrally with the two shielding members and the cam, so that an error due to backlash or the like between the driving device and the cam does not occur. Therefore, the position of the slit can be adjusted with high accuracy.

An X-ray CT apparatus according to the present invention includes a fixed frame, and a rotating frame rotatably supported by the fixed frame around an axis parallel to the width direction of the slit. The two shielding members, the cam and the driving device are supported via a guide shaft so as to be movable in the width direction of the slit, and the cam is sandwiched by the cam followers arranged in parallel along the width direction of the slit, and the slit is formed in the slit. Is rotated around a rotation axis parallel to the width direction of the
It is preferable that the dimension of the cam in the direction of the rotation axis at the contact position with each cam follower changes when the contact position changes by the rotation of the cam.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS X-ray CT apparatus 1 shown in FIGS.
Includes a tomographic image creation data collection unit 2, a bed 6 on which a subject 7 is placed, and a bed driving mechanism 8. The data collection unit 2 includes a gantry-shaped fixed frame 2a and this fixed frame 2a.
a has a short cylindrical rotating frame 2b supported rotatably about a horizontal axis, an X-ray irradiator 2c and an X-ray detector 2d attached to the rotating frame 2b. The inside is a tunnel 2e for subject placement. The bed driving mechanism 8 feeds the bed 6 into the tunnel 2e as shown by a two-dot chain line in FIG. While rotating the rotating frame 2b, the subject 7 on the bed 6
By irradiating X-rays from the X-ray irradiating device 2c and detecting X-rays transmitted through the subject 7 by the detector 2d, the subject 7 is scanned to collect data for tomographic image creation.

The rotating frame 2b is provided with a collimator 10 having a slit for guiding X-rays emitted from the X-ray irradiator 2c and transmitted through the subject 7 to the detector 2d. The rotating frame 2b rotates around an axis parallel to the width direction of the slit. The width of the slit becomes the slice thickness in CT imaging.

As shown in FIGS. 3A and 3B, the collimator 10 includes a pair of arched X-ray shielding members 11,
And slit width adjusting means for displacing both shielding members 11 so that the width of the slit changes. As a slit width adjusting means, there is provided a pair of cams 13 which are in contact with both shielding members 11 via cam followers 12. Both shielding members 11
Oppose each other via a space, and the space forms the slit 9. As shown in FIG. 5, each shielding member 11 is configured by attaching a lead shielding material 11b to an aluminum blade 11a. The cam followers 12 are configured by rollers that are rotatably attached to both ends of each shielding member 11.

The two shielding members 11 are connected to the rotating frame 2b via a pair of first guide shafts 20, a pair of second guide shafts 21, and a pair of bases 22 so as to be movable in the width direction of the slit 9. I have. Each guide shaft 20,
Reference numeral 21 has an axis parallel to the width direction of the slit 9. FIG.
As shown in FIG. 2, one end of each of the guide shafts 20 and 21 is fixed to the rotating frame 2b by a bolt (not shown).
2, each first guide shaft 20 is inserted into the positioning hole 2 b ′ of the rotating frame 2 b, and each second guide shaft 2
1 is inserted into a guide hole 2b "of the rotating frame 2b. Each guide shaft 20, 21 is fixed to a base 22 with a screw. One end of both shielding members 11 is connected to one first guide shaft 20, and the other end is connected. The other first guide shaft 20
Are slidably fitted in the width direction of the slit 9 via a slide bearing 23. As shown in FIG. 3 (2), at each end of both shielding members 11,
A spring receiver 25 attached to one shield member 11 and a spring receiver 25 attached to the other shield member 11 are connected by a spring 26, and each spring 26 acts on both shield members 11 to exert an elastic force to narrow the width of the slit 9. Let it. The spring 26
The width change of the slit 9 is regulated by pressing the two shielding members 11 against the cam 13 via the cam follower 12 by the elasticity of the slit 9. Both shielding members 11, both first guide shafts 20, both second guide shafts 21, and both bases 22
As shown in FIG. 3, the two bases 22 are connected by a jig 50 to form an assembly, which is attached to the rotating frame 2b in this assembled state. At this time, each guide hole 2
b ″ is made larger than the diameter of the second guide shaft 21;
By inserting the second guide shaft 21 into each guide hole 2b ", the assembly is roughly positioned with respect to the rotating frame 2b. Thereafter, each first guide shaft 20 is inserted into the positioning hole 2b '. The assembly is accurately positioned with respect to the rotating frame 2b, after which each base 22 is bolted to the rotating frame 2b.

The two shielding members 11 are displaced in the width direction of the slit 9 so that the width of the slit 9 changes by the operation of the cam 13. That is, at one end and the other end of both shielding members 11, the cam follower 12 on one shielding member 11 and the cam follower 12 on the other shielding member 11 are arranged in parallel along the width direction of the slit 9. (1)-of FIG.
As shown in (5), each cam 13 is integrated with a support shaft 30 having a rotation axis 30a parallel to the width direction of the slit 9, and in the present embodiment, is formed on a cylindrical surface centered on the rotation axis 30a. It has an outer peripheral surface 13 'along it. Each cam 13
Is a first cam contour surface 13 </ b> A in which one end face outer side is in contact with a cam follower 12 attached to one shielding member 11.
A second cam profile surface 1 whose outer side on the other end surface is in contact with a cam follower 12 attached to the other shielding member 11.
By being 3B, it is sandwiched by the cam followers 12. Each of the cams 13 is operated so as to rotate about the rotation axis 30a, and the operation changes the contact position with each of the cam followers 12, thereby displacing the two shielding members 11 and changing the width of the slit 9. I do.

The size of each cam 13 in the direction of the rotating shaft 30a at the contact position between the cam followers 12 is changed by the rotation of the cam 13 at the contact position. That is, each of the cams 13 of the present embodiment has a first portion 13a having a constant and maximum dimension in the direction of the rotation shaft 30a, which is the distance between the cam contour surfaces 13A and 13B, and the first portion 13a.
A second portion that gradually decreases in the direction of rotation from the portion 13a
A portion 13b, a third portion 13c having the same fixed size as the minimum size of the second portion 13b, and a third portion 13c
A fourth portion 13d having a smaller size than the fourth portion 13d and a fifth portion 13 having a smaller size than the fourth portion 13d.
e and a sixth portion 13f having a certain dimension smaller than the fifth portion 13e. FIG. 7 is an exploded view of a contact portion between the two cam contour surfaces 13A and 13B and the cam follower 12 in each cam 13, and the two cam contour surfaces 13A and 13B are symmetric with respect to one surface orthogonal to the rotation axis 30a. Shape. Thereby, the shape of each cam 13 is changed even if both shielding members 11 are displaced by the operation of the cam 13.
The center position of the slit 9 in the width direction is determined so as not to change. That is, the slit width adjusting means displaces both shielding members 11 in the width direction of the slit so that the center position in the width direction of the slit 9 does not change, and the width of the slit 9 is changed even if the width of the slit 9 changes. The centers in the directions are the same. Position adjustment is performed so that the center of the slit 9 in the width direction coincides with the center of the slice thickness in tomography.

A pair of driving devices 41 are provided for driving each cam 13 to rotate around the rotation shaft 30a. FIG.
As shown in (1) to (3), each driving device 41 has a motor base 42 and a stepping motor 43 attached to the motor base 42. Each motor base 42 is fitted to the first guide shaft 20 and the second guide shaft 21 so as to be movable in the width direction of the slit 9. The support shaft 30 is supported by the motor base 42 via a bearing, and the output shaft of the stepping motor 43 is connected to one end of the support shaft 30 via the coupling 44 without play. Thereby, the slit width adjusting means including both the shielding members 11 and both the cams 13 and the both driving devices 41 are supported via the first guide shaft 20 so as to be movable in the width direction of the slit 9, and are integrally formed with the slit. 9 can be displaced in the width direction.

One end of a male screw 51 is integrated with the other end of each second guide shaft 21,
The other end of the male screw 51 and one end of each male screw 51 are covered by the motor base 42, and the other end of each male screw 51 projects from the motor base 42, and the female screw member 52 is screwed to the projecting end. Each male screw 51 has a smaller diameter than the second guide shaft 21, and a spring 53 fitted on the outer periphery thereof is sandwiched between the second guide shaft 21 and the motor base 42.
The motor base 42 is pressed against the female screw member 52 by the elastic force of each spring 53. By rotating the female screw member 52 to change the screwing amount into the male screw 51, the motor base 42, the stepping motor 43, the cam 13, and the shielding member 11 move in the width direction of the slit 9 integrally. Therefore, the position of the slit 9 can be adjusted.
Each female screw member 52 has a long hole 52 along an arc around the rotation axis.
The female screw member 52 is fixed to the motor base 42 by a bolt (not shown) inserted into the long hole 52a, thereby restricting the rotation of the female screw member 52 and positioning the slit 9. The position of the slit 9 can be adjusted by rotating the female screw member 52 by loosening.

A disk 60 is attached to the other end of each of the support shafts 30.
The disk 60 has a large number of through holes formed at equal intervals along the circumferential direction, and a photo sensor 61 that detects each through hole is supported by the motor base 42. The detection signal of the through hole by the photo sensor 61 is transmitted as a rotation angle signal of the cam 13 to a control device (not shown) of the stepping motor 43, and the feedback control of the rotation step of the stepping motor 43 is enabled.

According to the above configuration, the stepping motor 4
The width of the slit 9 can be adjusted by displacing the two shielding members 11 only by operating the cam 13 by rotating the 3. At this time, even if the two shielding members 11 are displaced by the operation of the cam 13, the center position in the width direction of the slit 9 does not change, so that the width adjustment of the slit 9 does not affect the position of the slit 9. Furthermore, both shielding members 11 and cam 1
3 can be adjusted in the width direction of the slit 9 to adjust the position of the slit 9. At this time, since the two shielding members 11 and the cam 13 are displaced integrally, the position adjustment of the slit 9 does not affect the width of the slit 9. Thereby, the width adjustment and the position adjustment of the slit 9 can be performed individually without affecting each other. In addition, control when driving both shielding members 11 by the driving device 41 can be easily performed, and since there is no need to individually drive both shielding members 11, the structure can be simplified and downsized. Further, when the position of the slit 9 is adjusted, the driving device 41 for operating the cam 13 is displaced integrally with the two shielding members 11 and the cam 13, so that there is a play between the driving device 41 and the cam 13. Therefore, the position of the slit 9 can be adjusted with high accuracy.

The present invention is not limited to the above embodiment. For example, the shape of the cam is not particularly limited as long as the center position in the width direction of the slit is not changed even if both shielding members are displaced by the operation of the cam.

[0020]

According to the present invention, it is possible to provide an X-ray CT apparatus in which the width and position of the slit of the collimator can be easily and accurately adjusted, and the structure can be simplified and downsized.

[Brief description of the drawings]

FIG. 1 is a side view of an X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a rear view of the X-ray CT apparatus according to the embodiment of the present invention.

FIG. 3 is a front view of a collimator in an X-ray CT apparatus according to an embodiment of the present invention, and FIG.

FIG. 4 is a partially broken plan view of a main part of a collimator in the X-ray CT apparatus according to the embodiment of the present invention.

FIG. 5 is a partially broken front view of a main part of a collimator in the X-ray CT apparatus according to the embodiment of the present invention.

FIG. 6 is a front view, (2) is a plan view of a cam of a collimator in the X-ray CT apparatus according to the embodiment of the present invention,
(3) is a bottom view, (4) is a left side view, and (5) is a right side view.

FIG. 7 is an explanatory diagram of a shape of a cam of a collimator in the X-ray CT apparatus according to the embodiment of the present invention.

FIG. 8 is a partially broken plan view, (2) is a partially broken side view, and (3) is a rear view of the collimator driving device in the X-ray CT apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 2c X-ray irradiation device 2d X-ray detector 9 Slit 10 Collimator 11 Shielding member 12 Cam follower 13 Cam 41 Drive device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunari Tachibana 1-term, Kuwabaracho, Nishinokyo-ku, Nakagyo-ku, Kyoto-shi F-term in Shimadzu Corporation (reference) 2G088 EE02 FF02 JJ15 JJ22 JJ23 LL09 LL12 4C093 AA22 BA03 CA32 EB22

Claims (3)

[Claims] 1. An X-ray CT apparatus for guiding X-rays emitted from an X-ray irradiator and transmitted through a subject to a detector through a slit of a collimator, wherein the collimator passes through a space constituting the slit. It has a pair of X-ray shielding members facing each other, and a slit width adjusting means for displacing both shielding members so that the width of the slit is changed, and both shielding members and the slit width adjusting means are integrally formed. X-rays, which are displaceable in the width direction of the slit, and wherein the slit width adjusting means displaces both shielding members in the width direction of the slit so that the center position in the width direction of the slit does not change. CT device. 2. The slit width adjusting means has a cam which comes into contact with both shielding members via a cam follower, and both shielding members are arranged in the width direction of the slit such that the width of the slit is changed by the operation of the cam. The X-ray according to claim 1, wherein the X-ray is displaceable, and the shape of the cam is determined so that the center position in the width direction of the slit does not change even when the two shielding members are displaced by the operation of the cam. CT device. 3. A device according to claim 2, further comprising a driving device for operating the cam, wherein the driving device is displaceable in the width direction of the slit integrally with the two shielding members and the slit width adjusting means. X-ray CT device.