JPH07240296A - Grid control device of hot cathode three-pole x-ray tube used for khz repetitively pulsed x-ray device - Google Patents

Abstract

PURPOSE:To generate a stable repetitively pulsed X ray with the maximum 500kHz in a movable or fixed X-ray radiating time in the mus zone, by installing three sorts of grid control devices to an X-ray device having a capacitor and a hot cathode three-pole X-ray tube. CONSTITUTION:The electric charge of negatively charged capacitors 18 for grid voltage feeding, connected to a hot cathode three-pole are X-ray tube, is discharged, and then they are charged through a variable resistor 17 for X-ray time regulation, and those operations are repeated. And a capacitor 25 for constant grid voltage feeding, and a negatively charged capacitor 23 which is maintained at a stable charging voltage by a constant voltage diode 26, are connected to the grid 4, and a variable and positive high voltage pulse is applied repeatedly.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot cathode triode X-ray tube used in a repetitive pulse X-ray apparatus for medical diagnosis, high speed non-destructive testing, etc. The present invention relates to a grid control device used to drive a three-pole X-ray tube having a frequency of not less than kHz. In a conventional hot cathode triode X-ray tube used for a repetitive pulse X-ray apparatus for medical diagnosis and high-speed nondestructive testing,
A timer circuit is mainly used to generate a signal and the signal is input to the base of a transistor to adjust the X-ray irradiation time, but the repetition frequency is 1 kHz or less. Further, in a conventional two-pole X-ray tube having a hot cathode, a frequency of 1 kHz or less is obtained by using an inverter type high voltage transistor. When the purpose is focused on medical diagnosis, an X-ray apparatus which is currently used and has an X-ray irradiation time of 1 ms or more is used for high-speed dynamics such as contrast imaging of a circular artery. In this case, it is difficult to obtain a completely still image. In order to perform high-speed stroboscopic photography in the kHz range using the X-ray image intensifier, it is necessary to reduce the afterglow of the image intensifier.
In order to solve this, a pulse X-ray apparatus having a high X-ray irradiation time, a high frequency, a high dose rate and a high time resolution is required. A first object of the present invention is to adjust the X-ray irradiation time in the μs range by using a hot cathode triode X-ray tube grid control device with high time resolution, and if the variation in X-ray output is less than 1%. Moreover, it is necessary to obtain a frequency of about 100 kHz at maximum. A second object of the present invention is to provide a hot cathode triode grid control device capable of igniting a plurality of discharge high speed thyristors or discharge transistors connected in series at the same time and at high speed. Is. A third object of the present invention is to apply a positive pulse high voltage having a peak voltage of +10 kv or less to the grid of a three-pole X-ray tube and change the peak voltage to thereby apply voltage to the hot cathode. The tube current can be adjusted even when is fixed, and the maximum tube current is about 2 A, the X-ray irradiation time is about 1 μs, and the repetitive pulse X-ray with the maximum frequency of about 500 kHz is obtained. In order to solve the above-mentioned object, the present invention provides a high voltage charging terminal (a) between an anticathode (2) and a hot cathode (3) of a triode X-ray tube. Up to +1 via 7)
A high-voltage capacitor (5) for main discharge of about 1.5 μF, which is positively charged to 50 kV, is connected, and the grid (4) is controlled to charge the electric charge accumulated in the high-voltage capacitor (5) for main discharge. A grid control device for a hot cathode triode X-ray tube, which discharges pulse X-rays in a triode X-ray tube, wherein the grid (4) of the triode X-ray tube is connected to a grid charging terminal (8). And a grid voltage supply capacitor (18) that is negatively charged to a maximum of about −3 kV is connected to the grid voltage supply capacitor (1).
The discharge high-speed switching elements (20, 22) for discharging the electric charge accumulated in 8) are connected, and the primary coil of the insulation trigger transformer (13) is positively charged to about +100 V via the pulser charging terminal (9). The electric charge of the pulse generating capacitor (11) to be charged is transferred to the square wave input terminal (1
0) is input to the gate or the base of the high-speed switching device for discharge (12, 21) through the differentiating circuit (14, 15) and the voltage cut-off diode (16) to release the square wave, The gate or base of the discharge high speed switching device (20, 22) is connected to the secondary coil of the trigger transformer (13) through a pulse current supply capacitor (19). According to the present invention, a grid pulse transmission capacitor (23), which is negatively charged to a maximum of -3 kV, is connected to the grid (4) of a three-pole X-ray tube through a grid charging terminal (8) and is insulated. The secondary coil of the trigger transformer (13) is connected to the grid pulse transmission capacitor (23), and
A positive pulse high voltage of up to +10 kV generated in the next coil is applied to the grid (4) through the grid pulse transmission capacitor (23), and the grid current is generated to the grid pulse transmission capacitor (23). It is characterized in that the stored negative charges are discharged through a charge discharging resistor (24) to a rated voltage supplying capacitor (25) which holds a constant voltage by a constant voltage diode (26). It is what In the hot cathode triode X-ray tube lattice control device having the above-mentioned X-ray irradiation time adjusting function, a maximum of 100 kH of pulsed X-rays is adjusted to the required X-ray irradiation time in the μs range.
It is possible to output a pulsed X-ray with a maximum dose rate proportional to the tube current that is output at a high frequency of z and is approximately determined by the square of the charging voltage of the high-voltage capacitor for main discharge and the temperature of the hot cathode. it can. In the hot cathode triode X-ray tube grid controller as described above, a plurality of discharge high-speed thyristors and discharge transistors, and a plurality of pulse current supply capacitors are connected in series. The electric charge of the grid voltage supply capacitor negatively charged to about 3 kV can be discharged at the same time, so that the time resolution is good and the shortest is several μs.
Pulsed X-rays can be generated. In the hot cathode triode X-ray tube grid controller as described above, the grid voltage changes from 0 V during X-ray irradiation to the hot cathode 3.
Since the electron blocking voltage of the polar X-ray tube changes, and the electron focusing voltage also changes accordingly, it is easy to obtain an effective focal diameter with a uniform X-ray intensity distribution. Further, in a hot cathode three-pole X-ray tube grid control device in which the X-ray irradiation time is fixed and the tube current can be adjusted by the grid voltage, the temperature of the hot cathode is sufficiently raised to about 2000 K, and a positive pulse high voltage is applied to the grid. Is set so that the tube current is not saturated when the voltage is applied, and the lattice voltage can be boosted up to about +10 kV, so that the peak tube current can be increased to about 2A. In the hot cathode triode X-ray tube grid control device capable of adjusting the tube current by the grid voltage, the electron voltage from the hot cathode is made to be the anode by setting the grid voltage to a positive high voltage of about +10 kV at maximum. Can be focused. EXAMPLE In the example shown in FIG. 1, a vitreous tube (1) is used.
A high-voltage capacitor (5) for main discharge of about 1.5 μF is connected between the anticathode (2) of the triode X-ray tube with a hot cathode (3) and the hot cathode (3), The main discharging capacitor (5) is positively charged to a maximum of about +150 kV through the charging terminal (7), and the multiple grid voltage supplying capacitors (18) connected in series are connected to the charging terminal (8) for the grid. ) And a variable resistor for adjusting X-ray irradiation time (1
Negatively charge up to about -3 kV via 7). Further, the pulse generating capacitor (11) is positively charged to about +100 V through the pulse generating thyristor pulser charging terminal (9). Then, the square wave input from the square wave input terminal (10) is passed through a differentiation circuit including a differentiation circuit capacitor (14) and a differentiation circuit resistor (15) and a voltage cutoff diode (16) to generate a pulse thyristor. The charge accumulated in the capacitor (11) for pulse generation in the previous period is input to the gate of (12), and the thyristor (12) for pulse generation in the previous period.
Through the primary coil of the insulation trigger transformer (13). The pulse current generated in the secondary coil of the insulation trigger transformer (13) is input to the gates of a plurality of discharging high-speed thyristors (20) through a plurality of pulse current supplying capacitors (19), The electric charges accumulated in the grid voltage supply capacitor (18) are discharged at the same time using the discharging high speed thyristor (20). After that, the grid voltage supply capacitor (18) is charged again through the grid charging terminal (8) and the X-ray irradiation time adjusting variable resistor (17), and a plurality of the grids connected in series are charged. The charge accumulated in the high-voltage capacitor (5) for main discharge in the previous term is stored in the 3-pole X-ray tube in the voltage range from the charging voltage of the voltage supply capacitor (18) to the electron cutoff voltage of the 3-pole X-ray tube. To generate a pulse X-ray in the μs range. Further, an X-ray irradiation time proportional to the resistance value of the X-ray irradiation time adjusting variable resistor (17) can be obtained, and a repetition frequency of about 100 kHz at maximum can be realized. In the embodiment shown in FIG. 2, the discharging high speed thyristor (20) shown in FIG.
2) to replace the pulse current from the insulation trigger transformer (13) with a plurality of pulse current supply capacitors (1
By supplying it to the base of the transistor (22) for discharging in the previous period via 8), the electric charge of the capacitor (18) for supplying the grid voltage is discharged at a high speed. Other X-ray generation circuits are the same as those in FIG. In the embodiment shown in FIG. 3, the lattice pulse transmission capacitor (23) is negatively charged to a maximum of about -3 kV through the lattice charging terminal (8), and the pulse generation capacitor (11) is replaced by a thyristor pulser. It is positively charged to about +500 V through the charging terminal (9). Then, the square wave input from the square wave input terminal (10) is passed through a differentiation circuit including a differentiation circuit capacitor (14) and a differentiation circuit resistor (15) and a voltage cutoff diode (16) to generate a pulse thyristor. The charge stored in the pulse generating capacitor (11) is input to the gate of (12) and discharged to the primary coil of the insulation trigger transformer (13) through the pulse generating thyristor (12). A positive pulse high voltage of about +10 kV at maximum generated in the secondary coil of the trigger transformer (13) is applied to the grid pulse transmission capacitor (2
Apply to the grating (4) via 3). A capacitor for supplying a rated voltage of about 2 μF in which the negative charge accumulated in the pulse transmission capacitor (23) due to the lattice current generated by applying the positive pulse high voltage is kept at a constant voltage by the constant voltage diode (26). (25) Discharge resistor (24)
To discharge through. The electric charge accumulated in the main discharge capacitor (5) has a 3-pole X-ray in a voltage range from a high peak pulse voltage having a positive lattice voltage to a negative 3-pole X-ray tube electron cutoff voltage.
Since it discharges into the tube, it is possible to generate pulsed X-rays with an irradiation time of about 1 μs. Further, the tube current can be adjusted by changing the pulse high voltage applied to the lattice (4) to obtain a peak tube current of about 2 A at maximum.
Furthermore, a repetition frequency of up to about 500 kHz can be realized. Since the present invention is constructed as described above, it has the following effects. High-voltage capacitor for main discharge and hot cathode 3-pole X
By incorporating a grid control device driven at high frequency into an X-ray device having a ray tube, it is possible to obtain repetitive pulsed X-rays at a maximum of about 500 kHz. By changing the charging time of the grid voltage supply capacitor of the grid control circuit with a resistor,
The X-ray irradiation time can be adjusted accurately in the μs range, and the variation in the generated pulse X-ray intensity can be reduced to 1% or less. By applying a positive high voltage pulse to the grid of the hot cathode triode X-ray tube, repetitive pulse X-rays with a high dose rate can be obtained in an irradiation time of about 1 μs. Repetitive pulse X generated from an X-ray device incorporating these hot cathode triode X-ray tube grid control devices.
When the wire is applied to the medical and industrial fields, a maximum of 500 kH
High-speed flash photography of about z and high-frequency gas ionization are also possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of an electric circuit of a kHz repetitive pulse X-ray device having a thyristor type grating controller capable of adjusting an X-ray irradiation time in a μs range. FIG. 2 is a diagram showing another embodiment of the electric circuit of the kHz repetitive pulse X-ray apparatus having the transistor type grating control apparatus capable of adjusting the X-ray irradiation time in the μs range. FIG. 3 shows a repetitive pulse X having a fixed X-ray irradiation time and a grid control device in which a tube current can be adjusted by a pulse grid voltage.
It is a figure which shows one Example of the electric circuit of a line device. [Explanation of symbols] 1 glass tube body 2 anticathode 3 hot cathode 4 grid 5 high-voltage capacitor for main discharge 6 hot cathode DC power supply 7 high-voltage charging terminal 8 grid charging terminal 9 thyristor pulser charging terminal 10 square wave input terminal 11 Pulse Generation Capacitor 12 Pulse Generation Thyristor 13 Insulation Trigger Transformer 14 Differentiation Circuit Capacitor 15 Differentiation Circuit Resistor 16 Voltage Cutoff Diode 17 X-Ray Irradiation Time Adjustment Variable Resistor 18 Lattice Voltage Adjustment Capacitor 19 Pulse Current Supply Capacitor 20 Discharge high-speed thyristor 21 Pulse generation transistor 22 Discharge transistor 23 Lattice pulse transmission capacitor 24 Charge discharge resistor 25 Constant capacitance voltage supply large capacity capacitor 26 Constant voltage diode

Claims (1)

Claims [Claim 1] A maximum of +1 between the anticathode (2) and the hot cathode (3) of the triode X-ray tube via a high-voltage charging terminal (7).
A main discharge capacitor (5) of about 1.5 μF, which is positively charged to 50 kV, is connected, and the grid (4) is controlled so that the charge accumulated in the main discharge capacitor (5) is stored in the triode X-ray tube. A grid control device for a hot cathode triode X-ray tube that discharges and generates pulsed X-rays, wherein the grid (4) of the triode X-ray tube has a maximum of about -3 kV via a grid charging terminal (8). A grid voltage supply capacitor (18) that is negatively charged is connected, and a discharge high-speed switching element (18) that discharges the electric charge accumulated between the terminals of the grid voltage supply capacitor (18) is connected and insulated. From the pulse generating capacitor (11) and the square wave input terminal (10), which are positively charged to about + 100V to the primary coil of the trigger transformer (13) via the pulser charging terminal (9), to the differentiating circuits (14, 15). Voltage cut-off diode The switching element (12, 21) for inputting a square wave to the gate via (16) and discharging the electric charge accumulated in the pulse generating capacitor (11) via the primary coil is connected, The secondary coil of the trigger transformer (13) is connected to the gate of the discharge high-speed switching element (20, 22) through a gate pulse supply capacitor (19).
A grid control device for a hot cathode triode X-ray tube used for a Hz repetitive pulse X-ray device. [Claim 2] Between the anticathode (2) and the hot cathode (3) of the triode X-ray tube, a maximum of 15 is provided via a high-voltage charging terminal (7).
A main discharge high voltage capacitor (5) of about 1.5 μF that is positively charged to 0 kV is connected, and the grid (4) is controlled to charge the electric charge accumulated in the main discharge high voltage capacitor (5) into three poles. A grid control device for a hot cathode triode X-ray tube, which discharges pulse X-rays in an X-ray tube, wherein a maximum of − is provided on a grid (4) of the triode X-ray tube via a grid charging terminal (8). Lattice pulse transmission capacitor (23) that is negatively charged to about 3 kV
And a pulse generator capacitor (11) and a square wave input terminal (10) that positively charge the primary coil of the insulation trigger transformer (13) to about + 500V through a pulser charging terminal (9). A swinging element () for discharging a charge accumulated in the pulse generating capacitor (11) through the primary coil by inputting a square wave into the gate through (14, 15) and the voltage blocking diode (16). 12, 21) and the secondary coil of the insulation trigger transformer (13) is connected to the lattice pulse transmission capacitor (23) to generate a positive pulse high voltage of about +10 kV at maximum in the secondary coil. It is applied to the lattice (4) through the lattice pulse transmission capacitor (23), and the lattice current generated by the lattice pulse transmission capacitor (23) is applied to the lattice pulse transmission capacitor (23). The negative charges product constant voltage element (2
6) A hot cathode 3 used in a kHz repetitive pulse X-ray device, characterized in that it is configured to discharge by a rated voltage supply capacitor (25) and a discharge resistor (24) which are held at a constant voltage in 6). Grating control device for polar X-ray tube.