JPS5925360B2 - X-ray tube device for stereoscopic imaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray tube device for stereoscopic imaging for giving a three-dimensional effect to an X-ray image and for observing the three-dimensional positional relationship of a lesion.

Compared to the stereoscopic imaging method in which the X-ray tube is mechanically moved horizontally relative to the subject by the distance between the right and left pupils of a person and the images are taken twice, this method is for stereoscopic imaging in which the X-ray focus position is electrically moved. An X-ray tube device is also called a stereo X-ray tube device, and is a device that houses two triode X-ray tubes in one tube container and alternately irradiates X-rays by controlling the lattice of the tubes. A pair of cathodes and a grating are installed in the X-ray tube, and two focal points at a constant interval are alternately generated on the anode by controlling the grating. It has high diagnostic ability for such areas.

However, these conventional stereo X-ray tube devices not only have a complicated structure as described above, but also require an external bias power supply of about -2000V and a high-speed switching device for this, and a high-voltage cable to apply the bias voltage to the grid. Two cores are added to a 4-core or 3-core high-voltage cable with a pair of filament lines, and the cable socket on the tube cathode side requires a 5- to 6-core cable socket.There are a large number of component parts overall, and the problem is that they are more likely to fail. There was a point.

This invention was made in view of the above-mentioned current situation, and solves the problems of conventional stereo X-ray tube devices. By controlling the self-bias circuit based on the transient phenomenon of X-ray exposure configured by utilizing stray capacitance, there is no need for an external bias power supply and its switching device, which has the great effect of reducing manufacturing costs and increasing reliability. In addition, the number of core wires in the cathode side high voltage cable can be reduced, and the present invention aims to provide a device with a simple and robust cable socket and tube container structure.

That is, in a lattice-plane leg-shaped X-ray tube device that includes a grid and a pair of cathodes facing one anode in the tube,
One of the lines connected to the individual heating power sources of the pair of cathode filaments is alternately connected to a high voltage power source via a switch mechanism, and the filament lines connected to this switch mechanism are each connected to a self-bias conduction element. is connected to a common line connecting the pair of grids through a grid, and a grid bias voltage generated during a transition period when tube current begins to flow in the same way in each of the filament lines is applied to the tube of the filament line on the side not connected to the high voltage power supply. The present invention relates to an X-ray tube device for stereoscopic imaging characterized in that only the current is cut off and this state is maintained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the first embodiment of the apparatus, in which 1 is an X-ray tube container, 2 is a grid-controlled X-ray tube having two cathodes and a grid, and 3 is the X-ray tube. anode inside the tube,
4 and 5 are a pair of cathode filaments, and 6 and 7 are grids corresponding to the cathodes. In principle, the figure shows a net-like force in front of the filaments. In many current tubes, electron focusing in the cathode structure The walls are grid and have excellent emission characteristics.

Reference numeral 8 denotes a common grid control line that connects the pair of grids to each other and applies a bias voltage of the same potential.

9 is a filament heating device which has two heating transformers and a filament current stabilizing circuit, and has a heating current If4 of two filaments 4 and 5.

If, is controlled at a predetermined value.

Sa and Sb are, for example, the movable contacts of a reed switch with a withstand voltage of 5000V - C - The reed switch outer circumferential coils Ca and Cb are alternately energized with low DC voltage (several volts to several tens of volts) by the grid control circuit 12 at timings described later. Operation (
Turn on and off at high speed within 1m5ec using dotted lines a and b).

The figure shows a state where Sa is ON and Sb is OFF.

The common common Sc of sa and Sb is connected to one side of the high voltage rectifier 13.

A protective high voltage constant voltage element 1 is installed between the cable core wires 4L and 5L on the side where the contacts A and B of Sa and Sb are connected.
4 and diodes 15 and 16 are connected in anti-series, and their midpoint 11 is connected to the common grid control line Bvc.

The one-dot chain line 18 is a cable socket on the pole side of the tube container 1 (7) Is, and the socket part has four cores.

Cf is a stray capacitance existing between the cable core wires 4L and 5L, and is about 0.001 μF in this device.

On the high voltage power supply 13 side, H-T is high voltage transformer i, M
-8 is the X-ray exposure switch, 21 is the AC power supply, and other 22
．． 23 is the same as that in a general X-ray high voltage generator, but in the device of this invention, the timer 23 is
A manual changeover switch 24 is provided to set the operation to the timing explained in the time chart of FIG.

Sr is a command signal sent from the grid control circuit 12 to the timer 23.

When X-ray exposure is performed with the reed switch Sa in the ON state in the above configuration, the tube current I4. I flows into the filaments 4 and 5 as shown by dotted lines, and the tube current ■ from the filament 5 flows toward Sa in the direction of arrow C, charging the stray capacitance Cf, and bringing the core wires 4L to - and 5L to 10 potentials. to rise to.

As the potential of the core wire 4L, that is, the filament 4, decreases with time, the potential of the grid 6.7 decreases via the diode 15 to, for example, -2000 VDC, which cuts off the electron flow from the filament 6 to the grid 7, and at that moment, I , are turned off, and since one of the filaments 4 has the same potential, it continues to flow in the direction of the solid arrow.

This is the self-bias application function which is the essential part of the present invention, and the diodes 15 and 16 described above become self-bias conducting elements.

Although this diode is provided for the above purpose, it also has the function of biasing the glow discharge current flowing from the anode 3 to the grid 6.7 to the cable core wire 4L or 5L via the common line 8. ing.

When the tube current I flows for a predetermined exposure time, a focal point F4 is generated on the target of the anode 3, and imaging is performed from one direction.

Next, the effect of stereoscopic imaging will be explained using the time chart of FIG. 2.

Figure ■ is ON/OFF' of the above reed switch Sa, Figure ■
sb is ON-OFF, and FIG. 0 shows each timing of X-ray exposure.

The tl time in figure ■ is linked with the timer 23, and the X-ray exposure time is t3.
At the time when Sa is turned on earlier (ΔT1), sb is also turned on, but at t2, sb is turned off, resulting in the state shown in FIG.

The operation during X-ray exposure at t3 is as described above.
The actual time (Δt) from 3 to 13/ to cut off the tube current I, is extremely instantaneous, and now, for example, when I is 50
In the case of mA, Cf is charged by -2000V (EB) (△t) is determined by the following equation.

That is, it is 0.04 m sec, which is a short time that has no effect on the photographic darkening degree, so there is no problem even if two focal points occur simultaneously.

Next, for example, 0.1 sec of (t3'→1.)
After X-ray exposure between Ta was performed at focal point F4 with a tube current of ■4, M-8 was turned off by the operation of timer 23, and then (△T
3) At time t3, with a margin of sb fJooN
do.

Since both Sa and Sb are ON from t to t6, at t6 after the charging voltage (bias voltage) EB of Cf is completely discharged (ΔT4), the reed switches Sa and Sb in FIG. is completely reversed, and this time the electron flow from the filament 4 is cut off, I5 becomes a tube current, and a focus of F between TbO and F is formed on the target of the anode 3.

Since the distance between this F and the above-mentioned F4 is configured to be a predetermined distance, two-directional X-ray imaging can be performed six times per second at an interval of, for example, 0.1see.

The operations of the various parts from t7 to t in FIG. 2 are exactly the same as those from t3 to t6 described above, so a description thereof will be omitted.

As can be seen from the figure, the opening/closing operation of 3a tSb explained in FIG. The voltage applied to this SatSb is, for example, the first
In the state shown in the figure, the maximum bias voltage is 2000V between contact B of sb and common Sc.

This allows the use of the aforementioned reed switch with a withstand voltage of 5000 V class, making it easy to drive at low voltage and at high speed.

Next, second and third embodiments of the present invention will be explained with reference to FIGS. 3 and 4.

Both Figures 3 and 4 show only the parts of the configuration that are different from Figure 1, with the right side showing 20 halves of the tube, and the left side showing filaments 4 and 5.
The heating line extends to the inside of the room, and those with the same symbols as in Fig. 1 will not be explained.

FIG. 3 shows high resistance elements 31.1 as self-bias conducting elements in parallel with the diodes 15 and 16 described in FIG.
32 are connected.

In this case, when the reed switch Sa (not shown), that is, the cable 4L side, is turned ON, the tube current 2 flows in the direction of arrow d through the resistor 32 and the diode 15 as shown by the dotted line.There is a voltage drop across the resistor 32, that is, 5L. Ten potentials are generated at the intersection and one potential is generated at the intersection 17' with the grid control line 8, thereby self-biasing the grid 6.7.

At this time, a charging current also flows to Cf as shown by the dotted line of arrow C, and the bias voltage is maintained during X-ray irradiation, as shown in Fig. 2 [F
] t.

As described above, both 5atSb are turned ON between t6 and t6 (ΔT4) to discharge this charging voltage.

In this embodiment, the time during which the bias voltage is applied is longer than the charging time (for example, 0.04 sec, etc.) compared to the first embodiment.
The power to become faster ＼ As mentioned above, it is not enough time to be a problem.

Next, a third embodiment will be explained with reference to FIG.

This is the diode 1 from the one in Figure 3 as shown in Figure 1.
5.16 has been removed, and the symbols for each part have been omitted.

The effect is the same as described above, and a self-bias voltage is applied to the grid due to the voltage drop occurring across the resistor 320 and the charging of Cf. In this case, a glow from the anode 3 (not shown) to the grid 6. Since there are no diodes 15 and 16 for bypassing the discharge current, the above-mentioned influence remains to some extent.

The above are the configurations and functions of the three embodiments of the present invention, but the present invention is not limited to the illustrations and explanations, and includes devices other than high-speed stereoscopic imaging, and also includes devices that are not high-speed stereoscopic. It is applicable.

Further, devices without the timing control of FIG. 2 using a timer also fall within the scope.

Since the present invention is configured as described above, the conventional X-ray tube device for stereoscopic imaging requires an external high-voltage bias power supply, and the high-speed switching device and this bias application cable are connected to a two-core, X-ray tube device. Since it is added to the cathode side of the bulb, the overall structure is complex, has many parts, is expensive, and easily breaks down. This eliminates the drawbacks, and the tube current flow is improved by cleverly utilizing the stray capacitance of the filament heating circuit and a small number of electronic components. The self-bias voltage that occurs during the initial transition period is applied to the grid and maintained during X-ray exposure, which eliminates the need for an external bias power supply, switching device, and bias application cable, simplifying the structure and reducing production costs. The present invention provides a convenient device that is inexpensive, highly reliable, and capable of freely performing low-speed and high-speed stereoscopic imaging.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the structure of an X-ray tube device for stereoscopic imaging according to the first embodiment of the present invention, and Fig. 2 is a time chart explaining the operation of the above-mentioned device. FIG. 0 is a timing diagram of opening and closing of the switch, and FIG. 0 is a timing diagram of X-ray exposure. FIG. 3 is a block diagram of a second embodiment of the apparatus of the present invention, and FIG. 4 is a block diagram of the embodiment apparatus of FIG. 2... Lattice controlled X-ray tube having one anode and two pairs of cathodes/grids, 4, 5... 1 pair (c) frequent pole filament, 4L, 5L... 1 above One line (cable core line) Sa of a pair of filament heating circuits. sb...Movable contact of the switch mechanism (movable contact of the reed switch), Cal Cb...Operating coil of the switch mechanism (outer circumferential coil of the reed switch), 13...
High voltage power supply (high voltage generator including high voltage rectifier), 15
．． 16...Half-wave rectifier (diode) as a self-bias conduction element, 15,16,3L32...Parallel circuit of a half-wave rectifier (diode) and resistance element as a self-bias conduction element, 31°32. ... Resistance element as a self-bias conduction element, 8... A common line (grid control line) connecting two pairs of grids.

Claims (1)

[Scope of Claims] 1. In a lattice-controlled X-ray tube device comprising two pairs of cathodes facing one anode and a grid in a tube, the individual heating of each of the pair of cathode filaments is provided. One of the lines connected to the power source is alternately connected to the high-voltage power source via a switch mechanism, and the filament line on the side connected to this switch mechanism is connected to the pair of grids through a self-bias conduction element. A grid bias voltage that occurs during the transition period when the tube current begins to flow in the same manner in each of the filament lines is applied, and only the tube current of the filament line that is not connected to the high-voltage power supply is cut off, and this state is maintained. An X-ray tube device for stereoscopic imaging, which is characterized by: 2. The X-ray tube device for stereoscopic imaging according to claim 1, wherein the self-bias conduction element is a half-wave rectifying element and a resistance element in parallel, or one of them.