JP2001255288A - X-ray fluoroscope with camera tilting mechanism - Google Patents

Abstract

(57) [Problem] To provide an X-ray fluoroscope with a camera tilt mechanism in which the brightness of an X-ray transmission image does not change even when the tilt angle of the X-ray camera is changed. SOLUTION: A member (for example, in the case of a transmission type X-ray tube, a target 1b itself) whose thickness in the X-ray transmission direction continuously changes in the circumferential direction is provided near a window 1a of the X-ray tube 1. By rotating the member 1 b according to the tilt angle of the X-ray camera 4, the intensity of the X-ray output from the X-ray tube 1 is changed, and the X-ray traveling toward the X-ray camera 4 is changed. , The brightness of the X-ray transmission image of the sample W is always kept constant regardless of the tilt angle of the X-ray camera.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluoroscope for observing an X-ray fluoroscopic image of a specimen or constructing an X-ray CT image based on the fluoroscopic image data.
The present invention relates to an X-ray fluoroscope including a tilting mechanism of an X-ray camera.

[0002]

2. Description of the Related Art For example, in an X-ray fluoroscope such as an industrial X-ray fluoroscope, an X-ray tube comprising an image intensifier, a CCD camera, and the like is opposed to an X-ray tube.
An X-ray camera is arranged, and an X-ray transmission image of a symmetric object such as a sample placed between the X-ray cameras is taken by the X-ray camera. In addition, a fluoroscopic object such as a sample is usually placed on an XY table and a rotary table arranged between an X-ray tube and an X-ray camera so that X-ray transmission images in various directions and parts can be obtained. I will

[0005] Further, as schematically shown in FIG.
A camera equipped with a camera tilting mechanism 55 for tilting an X-ray camera 54 with respect to a rotary table 53 on which a ray tube 51, an XY table 52, and a sample W are placed has also been put to practical use.

[0004]

By the way, although an X-ray with a spread is output from an X-ray tube, its spatial intensity distribution is not generally uniform, and as shown in FIG. The portion (hereinafter referred to as the optical axis L) is the largest,
The further away from it, that is, the greater the angle with respect to the optical axis L, the weaker it becomes. Therefore, in the X-ray fluoroscope with the camera tilting mechanism described above, the X-ray camera 54
X-ray intensity incident on the X-ray camera 54 in a state where the tilt angle θ is located vertically above the ray tube 51 and the X-ray camera 54 is positioned on the optical axis L of the X-ray. Is maximum, whereas as the tilt angle θ increases, X
The X-ray intensity incident on the X-ray camera 54 decreases.

On the other hand, the intensity of the X-ray output from the X-ray tube 51 can be changed by adjusting the tube voltage and the tube current. The brightness of the image is set to be optimal, and this adjustment is usually performed in a state where the tilt angle θ of the X-ray camera 54 is zero.

Thus, in the conventional X-ray fluoroscope with a camera tilting mechanism, a good X-ray transmission image of the sample can be obtained when the tilt angle θ of the X-ray camera 54 is 0, but the tilting is not possible. When the X-ray camera 54 is tilted by the mechanism 55, there is a problem that the X-ray transmission image becomes dark due to insufficient X-ray intensity.

The present invention has been made in view of the above circumstances, and an X-ray fluoroscope with a camera tilting mechanism in which the brightness of an X-ray transmission image does not change even when the tilt angle of the X-ray camera is changed. It is intended to provide equipment.

[0008]

In order to achieve the above object, an X-ray fluoroscopic apparatus with a camera tilting mechanism according to the first aspect of the present invention is provided with an X-ray tube and an X-ray tube opposed to the X-ray tube. X
In the X-ray fluoroscopic apparatus having the X-ray camera and the tilting mechanism of the X-ray camera, the thickness in the X-ray transmission direction is increased in the circumferential direction in the vicinity of the window for extracting the X-ray from the X-ray tube. A continuously different member is provided rotatably, and the member is automatically rotated in such a direction that the thickness at the X-ray transmitting portion becomes thinner as the tilt angle of the X-ray camera becomes larger. It is characterized by having dynamic control means.

Here, in the invention according to claim 1,
When a transmission type X-ray tube is used, the target itself can be a member rotatably provided near the window (claim 2).

Further, in order to achieve the same object, a third aspect of the invention is provided.
An X-ray fluoroscopic apparatus with a camera tilting mechanism according to the present invention comprises an X-ray tube, an X-ray camera opposed to the X-ray tube, and an X-ray fluoroscope provided with a tilting mechanism of the X-ray camera. The apparatus further comprises X-ray tube control means for automatically changing the tube current of the X-ray tube or the tube current and the tube voltage so that the X-ray dose increases as the tilt angle of the X-ray camera increases. It is characterized by having.

According to the present invention, the intensity of X-rays output from an X-ray tube is automatically changed in accordance with the tilt angle of an X-ray camera. This is to keep the brightness constant.

That is, according to the first aspect of the present invention, an X-ray is provided near a window for extracting X-rays from an X-ray tube.
A member whose thickness in the X-ray transmission direction continuously changes in the circumferential direction is provided rotatably, and the member is rotated according to the tilt angle of the X-ray camera to automatically adjust the thickness at the X-ray transmission part. To change. As a result, the X-ray output from the X-ray tube undergoes attenuation according to its thickness when transmitting through the above-mentioned member. Therefore, as the tilt angle of the X-ray camera increases, X
By automatically rotating the member in a direction in which the thickness of the member at the X-ray transmitting portion is reduced, the X-ray intensity from the X-ray tube increases as the tilt angle of the X-ray camera increases, Due to the X-ray intensity distribution from the X-ray tube, a decrease in the X-ray intensity incident upon tilting of the X-ray camera can be offset, and the brightness of the X-ray transmission image can be kept constant. .

A second aspect of the present invention is a preferred embodiment of the first aspect of the present invention in which the X-ray tube is of a transmission type, that is, the X-ray tube has an electron beam irradiation surface and a target. As a type in which X-rays are taken out from the opposite surface, the target itself is rotatably arranged near the window of the X-ray tube, and the X-ray transmitting portion is set so that the target is tilted as the tilt angle of the X-ray camera increases. Therefore, it is rotated in a direction in which the thickness of the irradiated portion of the electron beam becomes thin. As a result, the X-ray intensity from the X-ray tube increases as the tilt angle of the X-ray camera increases, and the same effect as that of the first aspect can be obtained.

According to the second aspect of the present invention, there is no need to separately arrange a member for changing the amount of X-ray absorption by rotation in the X-ray tube, and this is included in the first aspect of the present invention. It can be said that this is the simplest and most efficient configuration. In the inventions according to claims 1 and 2, since the tube current or the like is not changed at all in order to change the X-ray intensity from the X-ray tube, the focus spot diameter of the electron beam applied to the target is enlarged. Does not occur, and a clear image can be obtained.

According to a third aspect of the present invention, when the tilt angle of the X-ray camera is changed, only the tube current of the X-ray tube is changed, or the tube current and the tube voltage are automatically changed. By changing the X-ray intensity, the tilt angle of the X-ray camera is increased and the intensity of the X-ray toward the X-ray camera is reduced. The relationship between the tube current of the X-ray tube and the intensity of the output X-ray, or the relationship between the tube current and the tube voltage and the intensity of the output X-ray, and the spatial intensity distribution of the X-ray from the X-ray tube are determined in advance. If measured and stored, only the tube current or the tube current and the tube voltage are appropriately changed in accordance with the change in the tilt angle of the X-ray camera, and the X-ray intensity toward the X-ray camera is kept constant. The X-ray intensity can be automatically changed as follows.

In the third aspect of the present invention, when the tube voltage is changed, the wavelength component of the X-rays changes. Therefore, it is desirable to change the X-ray intensity only by changing the tube current. If the required X-ray intensity cannot be obtained only by changing the X-ray intensity, the X-ray intensity may be changed by changing the tube current and the tube voltage.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the invention according to claims 1 and 2 of the present invention, and is a diagram showing both a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration. is there.

The X-ray tube 1 is disposed so that the optical axis L of the X-ray is directed vertically upward, and the XY along the horizontal plane is positioned above the X-ray tube.
A table 2 is provided, and a rotary table 3 is mounted on the XY table 2. An X-ray camera 4 is arranged above the turntable 3 at a predetermined distance from the turntable 3, and a perspective symmetric object W (hereinafter, referred to as a sample W) is placed on the turntable 3. X-rays are irradiated from below, and the X-rays transmitted through the sample W enter the X-ray camera 4. The X-ray camera 4 is, for example, a combination of an image intensifier and a CCD. The output of the X-ray camera 4 is taken into an image processing circuit 5 so that an X-ray transmission image of the sample W is displayed on a display 6. It has become.

The X-ray camera 4 can arbitrarily set the tilt angle θ of the X-ray tube 1 with respect to the optical axis L by the tilt mechanism 7. The tilting of the X-ray camera 4 is performed by driving the tilting motor 7a, thereby forming the X-ray camera 4 in an arc along a predetermined plane with the center of the X-ray tube 1 as a center.
This is done by moving

The X-ray tube 1 is a transmission type tube, and is shown in FIG.
(A) is an enlarged view of a main part of FIG. 1, and FIG. (B) is a view of the view taken in the direction of the arrow B. In order to extract X-rays, a window 1 a made of a light metal such as Be or Al is provided. At the same time, a substantially disk-shaped target 1b is arranged near the window 1a, and the target 1b is irradiated with an electron beam from behind the window 1a. And
X generated from the target 1b by electron beam irradiation
The line is on the surface opposite to the electron beam irradiation surface, that is, the window 1a.
Is output to the outside through the window 1a from the surface facing the.

The substantially disk-shaped target 1b is arranged with its center shifted with respect to the electron beam irradiation site, in other words, with its center shifted with respect to the center of the main body of the cylindrical X-ray tube 1. The casing of the X-ray tube 1 has an irregular shape in which the end on the side where the window 1a is disposed projects in a disk shape so as to cover the entire target 1b. Then, as shown in a perspective view in FIG. 3, this substantially disk-shaped target 1b has a tungsten (W) vapor-deposited film 1d formed on a surface of a base material 1c made of a light metal such as Al and having a thickness of about 0.5 mm. The thickness of the tungsten deposited film 1d is:
It changes continuously in the circumferential direction. A central portion of the base 1c is fixed to an output shaft of a motor 8 that passes through the casing in an airtight manner, and the target 1b is rotated by driving the motor 8. With such a configuration, the irradiation position of the electron beam on the tungsten deposition film 1d of the target 1b, that is, the thickness of the X-ray generation site is continuously changed by driving the motor 8.

Motor 8 for rotating target 1
And the tilting motor 7a, the driving motors 2a and 2b in each direction of the XY table 2, and the motor 3a for driving the rotary table 3, respectively, are provided in correspondence with each other, and It operates according to a drive signal from a drive circuit (both not shown) under the control of the control unit 9. The control unit 9 is mainly composed of a CPU, and is connected to an operation panel 10 for giving various instructions.

When the tilting mechanism 7 changes the tilt angle of the X-ray camera 4 by the tilt mechanism 7, the control unit 9 automatically controls the driving of the motor 8 in accordance with the tilt angle to control the target 1b.
Is rotated, the X-ray output from the X-ray tube 1 is
Even if the line intensity has the spatial distribution as shown in FIG. 6, the brightness of the X-ray transmission image of the sample W by the X-ray camera 4 is kept constant.

That is, when the tilting angle of the X-ray camera 4 is changed by the tilting mechanism 7, the control unit 9 drives the motor 8 to drive the target 1 b of the X-ray tube 1 at the irradiation position of the electron beam on the target 1 b. The thickness of 1d is automatically changed. Due to the change in the thickness of the tungsten deposition film 1d at the irradiation position of the electron beam, the target 1b
X-ray intensity generated from the opposite side of the electron beam irradiation surface and output to the outside through the window 1a changes.
The spatial intensity distribution of the X-rays from the X-ray tube 1 illustrated in FIG. 6 and the relationship of the X-ray intensity with respect to each rotation angle of the target 1b are written in the control unit 9 in advance,
The rotation angle of the target 1b is controlled so that the intensity of X-rays corresponding to the tilt angle θ of the X-ray camera 4 is always constant.

With the above operation, the tilt angle θ of the X-ray camera 4 can be arbitrarily set even if the spatial intensity distribution of the X-rays from the X-ray tube 1 has the distribution shown in FIG. Even if it is set, the intensity of the X-rays directed to the X-ray camera 4 is always constant, and the brightness of the X-ray transmission image of the sample W displayed on the display 6 can be kept constant.

It should be particularly noted in the above embodiment that the intensity of the X-ray output from the X-ray tube 1 is changed by changing the thickness of the target 1b itself at the irradiation position of the electron beam. With this configuration, it is not necessary to separately arrange a member for absorbing X-rays in the X-ray tube 1, and the X-ray intensity can be reduced with the most efficient and simple configuration. At the same time as changing the X-ray intensity, the electron beam spot applied to the target 1b does not change because the tube current and the tube voltage of the X-ray tube 1 are not changed. There is no danger that the sharpness of the X-ray transmission image will be reduced when changing.

In the above embodiment, the X-ray tube 1
By rotating the target 1b within the
Tungsten deposited film 1d at electron beam irradiation position
Although the X-ray intensity was changed by changing the thickness of the X-ray tube, a member capable of absorbing X-rays to a certain extent was rotatably provided between the window 1a of the X-ray tube 1 and the target 1b. Even when the thickness at the transmission part is changed according to the tilt angle θ of the X-ray camera 4, the same operation and effect as described above can be obtained,
In this case, without using a transmission type X-ray tube,
For example, an X-ray tube of a type that extracts X-rays from a direction orthogonal to the electron beam irradiation position may be employed.

Next, an embodiment of the invention according to claim 3 will be described. FIG. 4 is a diagram showing the configuration, in which a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration are shown together. In FIG. 4, members and the like equivalent to those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The feature of this example is that a normal X-ray tube 1 'is used and the tube current of the X-ray tube 1' or the tube current and the tube voltage are determined by the tilt angle of the X-ray camera 4. The point is that the X-ray intensity toward the X-ray camera 4 is kept constant by automatically changing the X-ray intensity in accordance with.

That is, in this embodiment, a tube current control circuit 11 and a tube current control circuit 11 capable of continuously changing the tube current and the tube voltage of the X-ray tube 1 'based on a command signal from the control unit 9 respectively. A tube voltage control circuit 12 is provided. The control unit 9 previously stores the relationship between the spatial intensity distribution of X-rays from the X-ray tube 1 'illustrated in FIG. 6 and the X-ray intensity for each value of the tube current of the X-ray tube 1'. And the relationship between the X-ray intensity for each value of the tube current and the tube voltage are written. Each time the tilting mechanism 7 changes the tilt angle θ of the X-ray camera 4, the X-rays directed to the X-ray camera 4 are changed. The tube current of the X-ray tube 1 'is changed so that the intensity of the X-ray becomes constant. If the required X-ray intensity cannot be obtained only by the change of the tube current, the tube voltage is added to the tube current. Change automatically.

According to this embodiment, the X-ray tube 1 '
Even when the spatial intensity distribution of X-rays from the camera is not uniform as illustrated in FIG. 6, when the X-ray camera 4 is tilted at an arbitrary tilt angle θ, it is output from the X-ray tube 1 ′. The X-ray intensity automatically changes, the X-ray intensity toward the X-ray camera 4 is kept constant, and the brightness of the X-ray transmission image displayed on the display 6 can be kept constant.

In this embodiment, the X-ray tube 1 '
X-ray tube 1 'by changing the X-ray intensity from
Although the electron beam spot applied to the target changes, there is an advantage that a normal X-ray tube 1 'can be used instead of a special one.

[0033]

As described above, according to the present invention, by automatically changing the intensity of the X-ray output from the X-ray tube in accordance with the tilt angle of the X-ray camera, X
Since the X-ray intensity toward the X-ray camera is always kept constant, the brightness of the X-ray transmission image does not change each time the tilt angle of the X-ray camera is changed, as in the related art. It is now possible to keep it constant.

According to the first and second aspects of the present invention, since the electron beam spot diameter and the like do not change when the X-ray intensity from the X-ray tube is changed, a clear X-ray transmission image is always obtained. Can be obtained.

According to the second aspect of the present invention, it is not necessary to separately provide a member for absorbing X-rays in the X-ray tube, and the X-ray intensity can be changed efficiently with a simple structure. Can be done.

On the other hand, in the invention according to claim 3, the spot diameter of the electron beam changes when the X-ray intensity is changed, but a normal X-ray tube can be used, and the mechanical structure Can be used, the structure of which is simple, and the desired effects of the present invention can be achieved relatively inexpensively.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the invention according to claim 1 and is a diagram showing both a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration.

FIG. 2 is an explanatory view of a structure of an X-ray tube 1 in the embodiment of FIG. 1, which is an enlarged view (A) of a main part of FIG. 1 and a view (B) of FIG.

FIG. 3 is a perspective view showing a detailed structure of a target 1b in the X-ray tube 1 in the embodiment of FIG.

FIG. 4 is a configuration diagram of an embodiment of the invention according to claim 3,
It is a figure which combined and shows the schematic diagram showing a mechanical structure, and the block diagram showing an electrical structure.

FIG. 5 is a schematic diagram illustrating a configuration example of a conventional X-ray fluoroscopic apparatus including a camera tilting mechanism.

FIG. 6 is a graph showing an example of a spatial intensity distribution of X-rays output from a normal X-ray tube.

[Explanation of symbols]

 1, 1 'X-ray tube 1a Window 1b Target 1c Base 1d Tungsten vapor deposition film 2 XY table 3 Rotary table 4 X-ray camera 5 Image processing circuit 6 Display 7 Tilt mechanism 7a Tilt motor 8 Motor 9 Control unit 10 Operation Panel 11 Tube current control circuit 12 Tube voltage control circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05G 1/32 H05G 1/32 A 1/34 1/34 A 1/64 1/64 EFterm (Reference) 2G001 AA01 BA11 CA01 DA01 DA02 DA09 GA13 HA13 JA01 JA06 PA11 PA12 4C092 AA01 AB02 AB22 AC11 BD05 BD14 BD20 BE04 BE06 CC04 CC12 CD02 CD03 CE01 CE02 CF08 CF35 CF43 CF47 DD06

Claims (3)

[Claims] 1. An X-ray fluoroscope comprising an X-ray tube and an X-ray camera opposed to the X-ray tube, and a tilting mechanism for the X-ray camera, comprising: X near the window for extracting X-rays
A member whose thickness in the radiation transmitting direction is continuously different in the circumferential direction is rotatably provided, and the thickness of the member at the X-ray transmitting portion is reduced as the tilt angle of the X-ray camera increases. An X-ray fluoroscopic apparatus with a camera tilting mechanism, comprising a rotation control means for automatically rotating in a certain direction. 2. The apparatus according to claim 1, wherein the X-ray tube is a transmission type X-ray tube, and the member is a target. 3. An X-ray fluoroscopic apparatus comprising an X-ray tube, an X-ray camera opposed to the X-ray tube, and a tilting mechanism for the X-ray camera, wherein the X-ray camera is tilted. X-ray tube control means for automatically changing the tube current of the X-ray tube or the tube current and the tube voltage so that the X-ray dose increases as the angle increases. X-ray fluoroscope with mechanism.