JPS5924487B2 - x-ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray tube used for stereo X-ray photography and the like.

Conventionally, one X-ray tube was used for stereo imaging.
Special Publication No. 41-21178 and Publication No. 48-2982
The structure shown in Publication No. 2 is known.

However, all of these methods form multiple X-ray focal points on one anode target, and therefore cannot increase the input.

In addition, since the electron beams emitted from the left and right cathodes are switched by blinking the filament, which is the electron radiation source, the left and right electron beams cannot be switched until the time required for the temperature of the filament to rise has elapsed. There is a time delay in taking a pair of X-ray pictures due to the line focus.

This is not suitable for photographing fast-moving objects such as blood flow.

On the other hand, semicircular anode targets are mounted on a rotor with their positions shifted in opposite directions, and X-rays with different focus positions are extracted using an electron beam emitted from one cathode. There is a technique disclosed in Japanese Patent Publication No. 39-18279.

In this case, the target cannot be rotated at a high speed of about 9,000 revolutions, which is impractical.

Furthermore, since the spacing between the cathode and the target is different, there is also the problem that the shape of the electron beam becomes irregular.

The present invention solves all of the drawbacks of the conventional structure as described above, and provides an X-ray tube with a hanging structure that increases the input capacity and allows the two X-ray focal points to blink freely.

In other words, its characteristic feature is that two disc-shaped rotating anode targets are arranged at a predetermined distance from each other within a vacuum envelope, and each target is bombarded with an electron beam. be.

Examples thereof will be described below with reference to the drawings.

Identical parts are designated by the same reference numerals.

Furthermore, in the embodiment shown in the drawings, the distance l between the two X-ray focal positions is
An example of an X-ray tube used for stereo X-ray photography is shown, in which the distance between the pupils is equal to that of a human being.

However, the present invention is not limited to this, and any X
It can be widely implemented in X-ray tubes having a line focal spacing.

The embodiment shown in FIG. 1 has the following structure.

That is, two disc-shaped umbrella-shaped rotating anode targets 12 and 13 are supported and provided opposite to each other at both ends of a vacuum envelope 11 that is generally cylindrical and made of an insulator such as glass. ing.

The distance l of the focal trajectory of target 12.13 is the pupillary distance (
55-70mm).

Further, the Targera H2, 13 are each fixed to a rotor 14.15 by a rotating shaft 16.17, and each rotor 14.15 is rotatably supported by a stator 18.19 sealed to the envelope. .

Two cathodes 20.21 that emit electron beams are placed in the middle of the two target lasers 1-12.13, facing each focal orbital plane, and these cathodes are located at the center of the side wall of the envelope. It is held by a stem 22 sealed to the section.

The spacing between the paired cathodes and targets is equal.

The X-ray tube of the present invention having the above configuration is easy to use for stereo X-ray tube imaging, etc., because the two pairs of anode targets and cathodes facing each other can be operated independently.

For example, if both cathodes are ignited in advance and an anode voltage is applied to each anode target at a desired time, X-rays will be generated immediately at that time.

This allows the time interval between the generation of X-rays from the two left and right targets to be set arbitrarily.

In practice, when performing stereo X-ray photography, it takes about 0.3 seconds to change the film for recording X-ray images, but the X-ray tube of the present invention can absorb X-rays from the left and right targets in this time. The outbreak can be well controlled.

Additionally, since each X-ray focus is obtained from an independent rotating anode target, input can be increased.

Note that it is also possible to extract X-rays from only one target if necessary, expanding the range of uses.

In addition, if the two targets are rotated in opposite directions, the X-ray tube and the
This is preferable because the mechanical stress generated between the wire tube and the device holding the wire tube becomes zero or close to zero.

Each cathode is not limited to one consisting of a filament serving as an electron emission source and a focusing electrode, but may be configured to include a control grid in front of the filament and control the generation of the electron beam by controlling the bias voltage of this grid. You can also do it.

The embodiment shown in FIG. 2 includes two anode targets 12.1.
3, the cathodes 20 and 21 are attached to the funnel-shaped portion 11a of the envelope 11, with the focal orbital planes facing oppositely to each other.
It is held by a stem sealed to 11b.

In the X-ray tube of this embodiment, since the stems holding the cathodes are attached to the respective targets, there are no restrictions on determining the distance between the two targets, and assembly is easy.

In this case as well, the spacing between the paired cathodes and targets is equal.

The X-ray tube of the embodiment shown in FIG. 3 or 4 has two targets supported on one rotating shaft 23.

This allows a single rotor to rotate both targets counterclockwise and at the same speed.

By the way, in the cathode 20, 21, as shown in FIGS. 5 and 6, the focusing electrode 25 surrounding the filament 24 is preferably formed of a magnetic material such as iron.

In the figure, reference numeral 26 is a focusing groove, 27 is a filament lead, and 27 is an insulator.

By using a magnetic material as the focusing electrode in this way, it is possible to prevent the trajectory of the electron beam traveling from the cathode to the anode target from changing over time due to the magnetic field for rotating the target.

In other words, minute fluctuations in the focal position can be suppressed.

This is particularly effective in an X-ray tube for stereo imaging such as the present invention, since self and mutual interference of the two sets of cathode-anode targets can be prevented.

The embodiment shown in FIGS. 7 and 8 is similar to that shown in FIG.
As shown in the figure, this cathode structure is suitable for an X-ray tube in which electron beams are emitted from approximately the same point for two anode targets.

That is, this cathode I has one filament 24 provided in the center.
Electron beams e and e are emitted in both directions from the center.

Focusing grooves 26a and 26b are formed on both sides of the focusing electrode 25, and control grids 31a and 31b are stretched outside of the focusing grooves 26a and 26b.

Bias voltages can be applied independently to the two grids 31a and 31b.

In the X-ray tube of this embodiment, one central filament is ignited, and the bias voltage of each control grid is controlled as desired to control the generation of the electron beam toward the target. I can do it.

That is, the filament remains ignited and the bias voltages of both control grids are maintained in a cut-off state when no electron beam is emitted to either target.

For example, when generating X-rays from one target, the bias potential of the corresponding control grid is made shallower to generate an electron beam.

Furthermore, when generating X-rays from the opposite side, the bias voltage of the control grid on the opposite side is controlled and operated.

Furthermore, they can also be generated simultaneously.

As described above, the X-ray tube of the present invention allows the two left and right X-ray sources to be switched over in a very short time and to operate simultaneously.

Therefore, stereo X-ray imaging of blood flow and other fast-moving objects can be fully realized.

Note that the electron emission source of the cathode is not limited to a directly heated filament, but may be an indirectly heated type, and may also be configured as a bifocal type with a plurality of cathodes for each anode target.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIGS. 2 to 4 are longitudinal sectional views each showing other embodiments of the invention, and FIG. 5 is a schematic diagram showing still another embodiment. FIG. 6 is a sectional view taken along line 6-6 in FIG. 5, and FIGS. 7 and 8 are sectional views of a clasp showing still another embodiment. 11... Vacuum envelope, 12.13... Anode target, e... Electron beam, 20,2L
30... Cathode, 23... Rotating shaft, 24...
...Filament (electron radiation source).

Claims (1)

[Scope of Claims] 1. Two disk-shaped rotating anode targets arranged at a predetermined distance from each other in a vacuum envelope, and an electron beam configured to strike each of the two rotating anode targets. An X-ray tube comprising: a cathode disposed in the X-ray tube; 2. The X-ray tube according to claim 1, wherein 22 rotating anode targets are supported at both ends of the vacuum envelope, and the cathode is installed at an intermediate portion between the two targets. 32 rotating anode targets are each supported at both ends of a vacuum envelope, and a cathode is supported on a side wall of the vacuum envelope corresponding to each target. wire tube. 2. The X-ray tube according to claim 1, wherein the 42 rotating anode targets are supported on a single rotating shaft. 5. The X-ray tube according to claim 1, wherein the cathode is formed so that an electron beam is emitted from one electron radiation source in two directions and impinges on two rotating anode targets. The X-ray tube according to claim 5, wherein the X-ray tube is configured so that the electron beams directed toward 62 rotating anode targets can be independently controlled.