JP2001170038A - Gantry rotation balance adjusting instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly precise gantry rotation balance adjusting instrument. SOLUTION: This instrument is comprised of a guide 103 mounted at least either in the radial direction or in the rotation axis direction of a rotary casing (gantry rotating part) 4, and a weight 105 mounted movably on the guide 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radiation CT (Compute
The present invention relates to a device for adjusting a rotational balance of a gantry rotating part of a d Tomography device.

[0002]

2. Description of the Related Art In a radiation CT apparatus, if the gantry rotating unit has an unbalance, vibration occurs when the gantry rotating unit is rotated, which has a great effect on image quality.

[0003] Therefore, parts (for example, a tube or a detector) in the gantry rotating section are manufactured during gantry manufacture.
When the ctor) is replaced, the rotation balance of the gantry rotating unit is adjusted.

[0004] On the other hand, there is a demand for reducing the inspection time by rotating the gantry rotating section at a high speed. The centrifugal force acting on the gantry rotation unit is proportional to the square of the rotation speed (angular velocity) of the gantry rotation unit.

For example, if the rotation speed of the gantry rotating section is doubled, the centrifugal force is quadrupled, and in order to suppress the vibration to the present level, the unbalance amount of the gantry rotating section is reduced by 1 /
Either four or four times the gantry rigidity.

[0006] Increasing the rigidity of the gantry increases the size of the apparatus and increases the cost. Therefore, it is desirable to reduce the amount of unbalance in the gantry rotating section. As a method for measuring the rotation balance of the gantry rotating section, the following method is used.

(1) Clockwise and counterclockwise starting torques of the gantry rotating section are measured with a spring scale or the like, and the unbalance of the gantry rotating section is measured from the difference between the two directions of starting torque.

(2) Parts other than the gantry rotating part, for example,
A vibration detecting means such as an acceleration sensor is provided in a frame, and the imbalance is measured from the vibration of the gantry rotating unit. (3) Insert a pin (pi) into the scan center of the gantry.
Arrange n), rotate the gantry rotation unit, and measure the imbalance of the gantry rotation unit from the shadow of the pin detected by the detector.

Then, according to the unbalance amount of the gantry rotating part measured by any of the above methods (1) to (3),
Adjustment of the rotation balance of the gantry rotating unit is performed by attaching a weight to the gantry rotating unit or removing a weight attached to the gantry rotating unit.

[0010]

However, in the method of adjusting the rotation balance of the gantry rotating section having the above-mentioned structure, the accuracy of the balance adjustment is not lower than the minimum weight of the weight (for example, 0.5 kg), and the accuracy is poor. There is a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly accurate gantry rotation balance adjusting device.

[0012]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is directed to a gantry rotating unit in a radial direction and a rotating shaft direction.
A gantry rotation balance adjusting device, comprising: a guide provided in at least one direction; and a weight movably provided on the guide.

When the guide is provided in the radial direction of the gantry rotating portion, the weight is moved along the guide to adjust the rotational balance of the gantry rotating portion in the radial direction.

When the guide is provided in the direction of the rotation axis of the gantry rotation unit, the weight is moved along the guide to adjust the rotation balance of the gantry rotation unit in the direction of the rotation axis.

Since the weight moves along the guide, the position of the weight can be changed continuously, and the accuracy of the balance adjustment is improved. Since the rotation balance can be accurately obtained, the occurrence of vibration is reduced.

Therefore, the gantry rotating section can be rotated at a high speed without increasing the rigidity of the gantry, which requires an increase in size and cost, thereby shortening the inspection time. According to a second aspect of the present invention, there is provided a driving unit for driving the weight according to the first aspect of the present invention along the guide, a vibration detecting unit for detecting a vibration of the gantry rotating unit, and rotating the gantry rotating unit. A control unit for driving the driving unit so as to reduce the vibration of the gantry rotating unit in response to a signal from the vibration detecting unit. .

The control means receives the vibration signal of the gantry rotating section from the vibration detecting means while rotating the gantry rotating section, and moves the weight along the guide via the driving means so as to reduce the vibration of the gantry rotating section. Change continuously.

By directly detecting the vibration of the gantry rotating section by using the vibration detecting means, the rotation balance can be adjusted with high accuracy. By rotating the gantry rotating unit at a high speed and generating a large vibration in the gantry rotating unit, more accurate rotation balance adjustment can be performed.

An acceleration sensor is used as the vibration detecting means.
(sensor), displacement sensor, strain sensor, etc., but are not limited thereto. Alternatively, a pin may be arranged at the scan center of the gantry, the gantry rotating unit may be rotated, and the vibration may be detected from the shadow of the pin detected by the detector.

Further, the vibration detecting means may be attached to the gantry in advance, or may be attached later. Further, in order to prevent the weight from moving along the guide due to centrifugal force when the gantry rotating section rotates at high speed, it is preferable to provide a lock means for inhibiting the weight from moving along the guide.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. First, the gantry will be described with reference to FIGS.

In FIG. 2, reference numeral 1 denotes a base placed on the floor. Reference numeral 2 denotes a sub-base provided to be tiltable in the front-rear direction with respect to the base 1. Reference numeral 3 denotes a fixed casing provided on the sub-base 2, and 4 denotes a rotating casing as a gantry rotating unit provided rotatably with respect to the fixed casing 3.

In FIG. 1, reference numeral 5 denotes a motor provided on the sub base 2 for driving the rotary casing 4 via a belt 6. The rotating casing 4 is provided with a tube 7 that is a radiation source that emits radiation to the subject 10 placed in the rotating casing 4, and a detector 8 that detects radiation transmitted through the subject 10. I have. or,
Reference numeral 9 denotes a collimator provided near the tube 7 for adjusting the radiation direction of the radiation of the tube 7.

The rotation of the rotating casing 4 by the motor 5 causes the tube 7 and the detector 8 to rotate around the subject 10, and the transmitted radiation transmitted through the subject 10 is detected by the detector 8. Such detection of transmitted radiation is called a scan, and a tomographic image of the subject 10 is reconstructed based on a plurality of views obtained by the scan.

The rotating casing 4 includes a rotating casing 4
First and second rotational balance adjusting devices 101 and 201 for adjusting the radial balance of the motor are provided. Next, the first and second rotational balance adjusting devices 201 and 301 will be described with reference to FIG. Since the first and second rotation balance adjusting devices 101 and 201 have the same structure,
The description will be made using the rotation balance adjustment device 101 of
The description of the second rotation balance adjusting device 201 is omitted.

A weight 105 is movably engaged with a guide 103 provided in the radial direction of the rotary casing 4. A female screw hole 107 is formed in the weight 105, and a screw rod 109 that is provided in parallel with the guide 103 and rotatably supported is screwed into the female screw hole 107.

One end of the screw rod 109 is connected to the output shaft of the brake motor 111. The brake motor 111 has an electromagnetic brake inside. When the motor is driven, the brake is released, and when the motor is stopped, the brake operates.

Also, as shown in FIG.
Is provided with an acceleration sensor 301 as vibration detecting means for detecting a vibration of the rotating casing 4 in a rotation plane direction.

Next, the electrical configuration of this embodiment will be described with reference to FIG. A motor 401 receives a signal from the acceleration sensor 301 and rotates the rotary casing 4 according to a program (procedure) 403 recorded in an IC memory such as a ROM or an auxiliary storage device such as a floppy disk or a hard disk. This is control means for controlling the brake motor 111 of the first and second rotation balance adjusting devices 101 and 201.

The control means 401, the program 403, and the acceleration sensor 301 may be incorporated in a radiation CT apparatus provided with a rotational balance adjusting device in advance, or when a service person or the like adjusts the rotational balance, the radiation CT apparatus may be used. It may be a form that can be connected to.

The operation of the above configuration will be described. (1) The control means 401 drives the motor 5 to rotate the rotary casing 4 at a low rotation speed.

(2) The control means 401 controls the acceleration sensor 30
1 to drive the brake motors 111 of the first and second rotational balance adjusting devices,
The weight 105 is moved along the guide 103 to a position where the signal of 01 becomes minimum.

(3) The control means 401 controls the rotation casing 4
Rotate faster than before. (1) to (3) are repeated until the rotational speed of the rotary casing 4 becomes the highest. According to the above configuration, the rotational balance of the rotary casing 4 in the radial direction can be adjusted.

Further, since the weight 105 of the first and second rotational balance adjusting devices 101 and 201 moves along the guide 103, the position of the weight 105 can be continuously changed, and the accuracy of the balance adjustment can be improved. Get better.

Since the rotation balance can be accurately obtained, the occurrence of vibration is reduced. Therefore, the rotating casing (gantry rotating unit) 4 can be rotated at a high speed without increasing the size and cost of the gantry rigidity, and the inspection time can be reduced.

By using the acceleration sensor 301 to directly detect the vibration of the rotating casing 4 which is a gantry rotating section, it is possible to perform accurate rotation balance adjustment.

By rotating the rotating casing 4 at a high speed and generating a large vibration in the rotating casing 4, more accurate rotation balance adjustment can be performed.
In this embodiment, the use of the brake motor 111 can prevent the weight 105 from moving along the guide 103 due to centrifugal force.

The present invention is not limited to the above embodiment. In the above-described embodiment, the acceleration sensor 301 is used as the vibration detecting means, but may be a displacement sensor, a strain sensor, or the like.

Alternatively, a pin may be arranged at the scan center of the gantry, the rotary casing 4 may be rotated, and vibration may be detected from the shadow of the pin detected by the detector 8. Further, the vibration detecting means may be attached to the gantry in advance, or may be attached later.

Although the brake motor 111 is used in the first and second second rotation balance adjusting devices 101 and 201 in the above embodiment, a normal motor may be used. In that case, a lock mechanism that inhibits the weight 105 from moving along the guide 103 may be separately provided.

Further, in the first and second rotational balance adjusting devices 101 and 201 of the above embodiment, the weight 105
Although the description has been given of the configuration in which the member moves along the guide 103, in FIG. 3, a member corresponding to the weight 105 is fixed to the rotating casing 4, and the brake motor 111 which becomes the weight by rotating the 10
A configuration in which the rotating casing 3 is moved in the radial direction of the rotating casing 4 may be employed.

Further, in the above embodiment, the first and the second for adjusting the rotational balance of the rotary casing 4 in the radial direction are provided.
The rotation balance adjustment devices 101 and 201 are provided. However, in order to adjust the rotation balance of the rotation casing 4 in the rotation axis direction, as shown in FIG. It is sufficient to provide a third rotation balance adjusting device 501 in which the weight 105 moves in the rotation axis direction of the rotary casing 4 with a similar configuration.

When adjusting the rotational balance of the rotary casing 4 in the direction of the rotational axis, the control section 401 performs the following operation. (1) The control means 401 drives the motor 5 to rotate the rotary casing 4 at a low rotation speed.

(2) The control means 401 controls the acceleration sensor 30
Receiving the signal from the first rotation balance adjusting device 50
The first brake motor 111 is driven, and the acceleration sensor 30
The weight 105 is moved along the guide 103 along the rotation axis direction of the rotary casing 4 to a position where the signal of 1 becomes minimum.

(3) The control means 401 controls the rotating casing 4
Rotate faster than before. (1) to (3) are repeated until the rotational speed of the rotary casing 4 becomes the highest. According to such a configuration, the rotational balance of the rotary casing 4 in the rotation axis direction can be adjusted.

Moreover, the third rotational balance adjusting device 50
Since the first weight 105 moves along the guide 103,
The position of the weight 105 can be continuously changed, and the accuracy of balance adjustment is improved.

Since the rotation balance can be accurately obtained, the occurrence of vibration is reduced. Therefore, the rotating casing (gantry rotating unit) 4 can be rotated at a high speed without increasing the size and cost of the gantry rigidity, and the inspection time can be reduced.

By using the acceleration sensor 301 to directly detect the vibration of the rotating casing 4 which is a gantry rotating section, it is possible to adjust the rotational balance with high accuracy.

By rotating the rotary casing 4 at a high speed and generating a large vibration in the rotary casing 4, more accurate rotation balance adjustment can be performed.
And, in order to adjust the rotational balance of the rotary casing 4 in the radial direction, first and second rotational balance adjusting devices 101 and 201 are provided. Further, in order to adjust the rotational balance of the rotary casing 4 in the rotational axis direction. , A third rotational balance adjusting device 501 may be provided.

In this case, the rotational balance adjustment of the rotary casing 4 in the radial direction and the rotational balance adjustment of the rotary casing 4 in the rotational axis direction can be performed with high accuracy.

[0051]

As described above, according to the present invention, a highly accurate gantry rotation balance adjusting device can be realized.

[Brief description of the drawings]

FIG. 1 is a front view of a gantry of an embodiment provided with a rotation balance adjusting device of the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is an enlarged view of the rotation balance adjusting device of FIG. 1;

FIG. 4 is a block diagram illustrating an electrical configuration of the embodiment.

FIG. 5 is a diagram for explaining another embodiment.

[Explanation of symbols]

 4 Rotating Casing (Gantry Rotating Part) 101 First Rotary Balance Adjuster 103 Guide 105 Weight 109 Screw Rod 111 Brake Motor 201 Second Rotary Balance Adjuster

Claims (2)

[Claims] 1. A gantry comprising: a guide provided in at least one of a radial direction and a rotational axis direction of a gantry rotating portion; and a weight movably provided on the guide. Rotation balance adjustment device. 2. A driving unit for driving the weight along the guide, a vibration detecting unit for detecting vibration of the gantry rotating unit, and a signal from the vibration detecting unit while rotating the gantry rotating unit. 2. The gantry rotation balance adjusting device according to claim 1, further comprising: control means for driving the driving means so as to reduce vibration of the gantry rotating unit.