JPH0216531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic aging device for stabilizing the output of an X-ray tube before X-ray imaging in an X-ray imaging apparatus.

As is well known, when the X-ray tube is energized immediately after the power is turned on or after a long period of rest, the output of the X-ray tube is unstable, so be sure to check the X-ray tube under appropriate load conditions before using it for X-ray photography. A break-in operation, a so-called aging operation, is performed.

This aging operation causes electric charge (wall charge) attached to the inner wall of the X-ray tube to attach to the anode, etc., and at the same time makes the potential distribution inside the tube static.
The purpose is to forcibly discharge and remove roughness (microprotrusions, etc.) on the electrode portion, thereby stabilizing the X-ray output during X-ray photography.

In the above system, if imaging conditions are suddenly applied to the X-ray tube at the initial stage, there is a high possibility that creeping discharge will occur on the tube wall due to wall charge. Therefore, it is preferable to perform a minute discharge under fluoroscopic conditions until the potential distribution within the tube settles down, and then gradually shift the load to the maximum load condition during imaging.

However, the aging conditions mentioned above have not been established, and since the aging process generally relies on the experience of engineers, the load conditions vary, and there is a risk of accidents such as damage if aging is performed incorrectly or if aging is forgotten. Ta.

Recently, computerized tomography equipment, so-called CT (Computed Tomography), has become a type of X-ray tomography.
Tomography) is in practical use, but this
Many CT systems use high-power pulsed X-rays, and for X-ray tubes that output high-power pulsed X-rays, there is a risk of the above-mentioned X-ray tube breakage accident, especially during aging operations. was big.

This invention has been made in light of the above circumstances, and is based on the experimental determination of aging conditions suitable for pulsed X-ray generators such as CT, and automatic aging using a program created based on the aging conditions. An object of the present invention is to provide an automatic aging device that performs an aging operation.

Here, the aging conditions suitable for a pulsed X-ray generator such as a CT are experimentally as shown in FIG. 1. (In addition, tube voltage KVp, tube current m
A. The value of the exposure time t is an example. ) i.e.
The tube voltage is gradually increased from the minimum value (60 KVp) to the maximum value (120 KVp) using the tube current (4 mA) under fluoroscopic conditions, and is further maintained at the maximum value for a predetermined period of time to irradiate X-rays. (2 minutes in total) Next, the imaging conditions of tube current and tube voltage (500mA-
90KVp, 400mA-100KVp, 375mA-
Pulsed X-rays are sequentially irradiated under the same conditions and at the same period (100KVp, 350mA-120KVp).

The structure of an embodiment of the automatic aging apparatus of the present invention for carrying out the above aging will be described below with reference to FIGS. 2 to 5.

Figure 2 shows the X-ray high voltage generation circuit, where HT is the Y-connected primary winding L ₁ , the Y-connected and △-connected secondary windings L ₂₁ ,
It is a three-phase high voltage transformer consisting of _L22 . primary winding
The input terminal of L ₁ is connected to the three-phase AC power supply 3φAC,
The neutral points are separated and connected to the input terminals of a switching circuit SW for opening and closing the neutral points. The output terminals of the secondary windings L ₂₁ and L ₂₂ are connected to the input terminals of the high voltage rectifiers HD ₁ and HD ₂ , respectively. High-voltage capacitors HC _{1 ,} HC _{2 ,} bleeder resistors Rb ₁ , Rb ₂ , and charging voltage detection resistors Rd ₁ , Rd ₂ are connected in parallel to the output terminals of the rectifiers HD 1 and HD 2, respectively. positive terminal of capacitor HC ₁ ,
The negative terminal of capacitor HC ₂ is connected to a separate high-voltage switching tube, namely tetrode tube TT ₁ , TT ₂
are respectively connected to the anode and cathode of the X-ray tube XT through. The switching circuit SW includes a three-phase rectifier D 0 connected to the neutral point separation terminal of the primary winding L ₁ of the high voltage transformer HT, and a first thyristor SCR ₁ for closing connected between the output terminals of the three-phase rectifier D ₀ . , a second opening thyristor SCR ₂ , a resonance coil L ₀ and a capacitor C ₀ are connected in parallel. Also, the first and second thyristors
Each gate terminal of SCR ₁ and SCR ₂ is connected to a rectifier.
It is connected to the secondary windings of pulse transformers PT ₀₁ and PT ₀₂ via D ₀₁ and D ₀₂ . The tetrode tubes TT ₁ , TT ₂ have switching control circuits SC ₁ ,
Each is connected to SC ₂ . The switching control circuits SC ₁ and SC ₂ have the same configuration and supply control voltages -Eg ₁ and +Eg ₂ to the first and second grids of the tetrode tubes TT ₁ and TT ₂ , respectively, and
The collector and emitter of an NPN transistor _TR0 are connected in the forward direction between the first grid and the cathode. The base of the transistor TR ₀ is connected to the secondary windings of pulse transformers (isolation transformers) PT ₁ and PT ₂ via a base resistor R ₀ and a rectifier D ₁ . The primary windings of the pulse transformers PT ₀₁ and PT ₀₂ are shown in FIG. The high voltage capacitor HC ₁ ,
Each is connected to the output terminal of the charging pressure control circuit of HC ₂ . In addition, the charging pressure detection resistor
Rd ₁ and Rd ₂ are respectively connected to input terminals of the charging voltage control circuit.

In the charging voltage control circuit (Fig. 3), the resistor Rd ₂ is connected to the inverter operational amplifier AP ₁ and the input resistor R ₂ , and the resistor Rd ₁ is connected to the input resistor R ₁
is connected to the input terminal of the summing operational amplifier AP ₂ via the summing amplifier AP 2. The output terminal of amplifier AP ₂ is the input resistance
It is connected to the inverting input terminal of the comparison operational amplifier AP ₃ via R ₃ . The inverting input terminal of the amplifier AP ₃ is also connected to the output terminal of the integrating operational amplifier AP ₄ via an input resistor R ₄ and an analog switch AS ₀₁ . The amplifier AP ₄ has an integrating power supply +Es ₁ connected to its inverting input terminal, and a discharging analog switch AS ₀₂ is connected to a resistor R ₅ between both terminals of the integrating capacitor C ₂ .
A constant voltage zener diode ZD is connected between the output terminal and ground. The inverting input terminal of the amplifier AP ₃ also corresponds to the reference voltage setting tube voltage via an input resistor R ₆ . ) −Es ₂₁ , −Es ₂₂ −Es ₂₃ , −Es ₂₄ are connected to each other via analog switches AS ₁₀ , AS ₂₀ , AS ₃₀ , AS ₄₀ and input resistors R ₇ , R ₈ , R ₉ , R ₁₀ respectively. connected in parallel. The output terminal of the amplifier AP ₃ is connected to the first input terminal of the NOR gate NR ₁ , and is also connected to the trigger input terminal of the monomultivibrator MM ₁ via a differentiator circuit consisting of a capacitor C ₃ and a resistor R ₁₁ and an inverter IN ₁ . It is connected to the. The phase inversion output terminal (hereinafter referred to as the output terminal) of the mono multivibrator MM ₁ is a NOR gate.
Connected to the first input terminal of NR ₂ . For example, each second input terminal of NOR gate NR ₁ and NR ₂ has
The output terminal of a pulse generator PG ₁ consisting of an astable multivibrator with a repetition period of 20 KHz is connected. The output terminals of NOR gates NR ₁ and NR ₂ are connected to the bases of transistors TR ₁ and TR ₂ via base resistors R ₁₂ and R ₁₃ , respectively, and are connected to inverters IN ₂ and IN ₃ and base resistors R ₁₄ and 2, respectively.
It is connected to the bases of transistors TR ₃ and TR ₄ via R ₁₅ . The collectors of transistors TR ₁ and TR ₂ are connected to the DC drive power supply + via resistors R ₁₆ and R ₁₇ .
Vcc, and each emitter is connected to the pulse transformer TP ₀₁ , through the capacitor C ₄ , C ₅ .
It is connected to the primary winding of TP ₀₂ and to the collectors of transistors TR ₃ and TR ₄ , respectively. The emitters of transistors TR ₃ and TR ₄ are both grounded.

The tube current control circuit (Fig. 4) includes a rectifier D ₂ to which the AC power supply AC is connected to the input terminal, a smoothing coil L ₃ and a capacitor C ₆ , a control transistor TR ₅ , and a ripple removal resistor R ₁₈ ,
The positive output terminal of the DC power supply circuit DC consisting of the capacitor _C7 is connected to the intermediate tap of the primary winding of the pulse transformer (isolation transformer) _TP3 . Both terminals of the primary winding of TP ₃ are connected to transistors TR ₆ ,
Connected to the TR ₇ collector. transistor
The emitters of TR ₆ and TR ₇ are both grounded, and the non-phase inverted output terminal (hereinafter referred to as Q output terminal) output terminal of the J-K type flip-flop FF ₁ is connected to the base of the driver DV ₁ , DV ₂ and the resistor R ₁₉ , Each is connected via R ₂₀ . The J-K input terminal of the flip-flop _FF1 is clamped to a high level voltage +Vcc, and the output terminal of the pulse generator _PG2 is connected to the clock input terminal (Cp). These transistors TR ₆ TR ₇ , flip-flop FF ₁ , and pulse generator PG ₂ constitute a DC voltage chopping circuit. An output voltage detection resistor _R21 is connected between the output terminals of the DC power supply circuit DC, and the detection output terminal of the resistor _R21 is connected to an operational amplifier for error amplification.
Connected to the inverting input terminal of AP ₅ via input resistor R ₂₂ . The non-inverting input terminal of amplifier AP ₅ is a resistor
Grounded through R ₂₃ and reference voltage +
Es ₃₀ , +Es ₃₁ , +Es ₃₂ , +Es ₃₃ , Es ₃₄ are analog switches AS ₁₁ , AS ₁₂ , AS ₁₃ , AS ₁₄ , AS ₁₅ and input resistances R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ are connected in parallel to each other via. The output terminal of the amplifier _AP5 is connected to the base of the transistor _TR5 of the DC power supply circuit DC via a resistor _R29 . A rectifier _D3 and a smoothing capacitor _C8 are connected between the output terminals of the secondary winding of the pulse transformer _TP3 .
Connected to the filament of wire tube XT.

FIG. 5 shows a circuit that controls the load conditions of the X-ray tube and the X-ray exposure timing. That is,
One end of the PS is grounded at the X-ray tube automatic aging start command switch, and the other end is connected to the DC drive power supply +Vcc via a pull-up resistor _R30 .
Mono multivibrator via inverter IN ₄
Connected to the trigger input terminal of MM ₂ . The mono-multivibrator _MM2 is an X-ray exposure timer (for example, 2 minutes) under fluoroscopic conditions, and its output terminal is connected to an R-S type flip-flop FF via a differential circuit consisting of a capacitor _C9 and a resistor _R31 , and an inverter _IN5 . ₂ , _FF0 , and _FF3 , and is also connected to the gate of the analog switch _AS02 of the charging voltage control circuit in FIG. ₃ via the driver _DV0 . 1
is connected to the input terminal of Noah Gate NR ₃
The output terminal of the pulse generator PG ₄ is connected to the second input terminal of the pulse generator PG 4 . The output terminal of the flip-flop FF ₂ is connected to the set input terminal of the R-S type flip-flop FF ₈ via a differentiator circuit consisting of a capacitor C ₁₅ and a resistor R ₅₁ and an inverter IN ₇ , and a reset input terminal is used for comparison of the charging voltage control circuit. Amplifier AP ₃
is connected to the output terminal of flip flop
The Q output terminal of FF ₈ is connected to an analog switch for controlling the oscillation of pulse generator PG ₃ via driver DV ₁₀ .
Connected to the gate terminal of AS ₀ . This pulse generator PG ₃ includes, for example, an integration circuit consisting of the oscillation control analog switch AS ₀ , a resistor R ₀₁ , and a capacitor C ₀₁ , and a unidirectional transistor UJT.
and a mono multivibrator MM _0. When the analog switch AS ₀ is closed, the unidirectional transistor UJT is turned on and off by the change in the output voltage of the integrating circuit, and as a result, the mono multivibrator is activated at a predetermined period. It is configured so that a pulse is oscillated from vibrator MM ₀ . The output terminal of this pulse generator PG ₃ is the first one of the NOR gate NR ₇ .
It is connected to the input terminal of the counter CT, and also to the count input terminal (CK) of the counter CT. Counter CT is a 4-bit binary counter, and its binary output terminal is connected to the input terminal of decoder DD. The decoder DD decodes the input binary signal into a decimal number, and converts the decimal number into a corresponding "0" as a low level signal (hereinafter referred to as "0").
~ Derived to output terminal "8". In the decoder DD, the "2" output terminal is the reset input terminal of flip-flop FF ₃ , the set input terminal of flip-flop FF ₄ , and the "4" output terminal is the flip-flop FF _4.
The reset input terminal of flip-flop FF 5, the set input terminal of flip-flop FF ₅ , the "6" output terminal is the reset input terminal of flip-flop FF ₅ , the set input terminal of flip-flop FF 5,
The set input terminal and "8" output terminal of FF ₆ are connected to the reset input terminals of flip-flops FF ₆ , FF ₈ , and FF ₀ and the clear input terminal (CL) of counter CT, respectively. flipflop FF ₀ ,
Each output terminal of FF ₃ to FF ₆ has a separate driver DV ₃ ,
DV ₄ , DV ₅ , DV ₆ , DV ₇ to the analog switch AS ₀₁ of the charging voltage control circuit in FIG.
AS ₁₀ , AS ₂₀ , AS ₃₀ , AS ₄₀ and analog switches of the tube current control circuit in Fig. 4 AS ₁₁ , AS ₁₂ ,
Separate resistors to the gate terminals of AS ₁₃ , AS ₁₄ , and AS ₁₅
R ₃₆ , R ₃₇ , R ₃₈ , R ₃₉ and R ₄₀ , R ₄₁ , R ₄₂ , R ₄₃ ,
Connected via _R44 . The output terminal of NOR gate NR ₇ is connected to each first input terminal of NOR gates NR ₄ and NR ₅ . Noah Gate NR ₄ ,
For each second input terminal of NR ₅ , J and K terminals are “1”
J-K type flip-flop FF ₇ clamped to
are connected to the Q output terminal and output terminal, respectively. The clock pulse input terminal of flip-flop _FF7 is connected to the output terminal of NOR gate _NR8 . The output terminals of NOR gates NR ₄ and NR ₅ are connected to the first and second input terminals of NOR gate NR ₈ , respectively, and are connected to resistors R ₄₆ and R ₄₇ respectively.
are connected to the bases of NPN-type transistors TR ₈ and TR ₉ via . transistor
TR ₈ and TR ₉ each have a diode D ₁₀ and D ₂₀ in their collectors.
respectively through the pulse transformer PT ₁ ,
(PT ₂ ) are connected to each end of the primary winding,
Each emitter is grounded. pulse transformer
The intermediate tap of PT ₁ (PT ₂ ) is connected to the DC drive source +V _DD . In addition, "8" of the decoder DD
The output terminal is also connected to the set input terminal of an R-S type flip-flop FF ₁₀ via a differentiator circuit consisting of a capacitor C ₁₄ and a resistor R ₄₉ and an inverter IN ₁₂ . The set output terminal of flip-flop FF ₁₀ is commonly connected to the first and second input terminals of driver gate NG ₂ , and is also connected to an X-ray controller (not shown). The output terminal of driver gate NG ₂ is connected to the DC drive power supply + via resistor _R53 .
Lamp (or buzzer) LM connected to V _DD
It is connected to the. Next, the operation of the above configuration will be explained with reference to FIG.

That is, since the flip-flop _FF0 in FIG. 5 is normally in the reset state, its reset output "1" causes the analog switch of the charging voltage control circuit in FIG. ₃ to be activated via the driver DV3.
AS ₀₁ and analog switch AS ₁₁ of the tube current control circuit in FIG. 4 are closed. Therefore,
Since the analog switch AS ₀₁ is closed, both ends of the capacitor C ₂ of the integrating amplifier AP ₄ are short-circuited, and the amplifier AP 4 becomes a simple amplifier with the resistor R ₅ as a feedback resistor. In this case, the output of this amplifier AP ₄ is at an output level corresponding to the tube voltage (the total charging voltage of both the high voltage capacitors HC ₁ and HC ₂ ),
The high voltage capacitors HC ₁ and HC ₂ already have the minimum tube voltage,
For example, a voltage of 60KVp is charged. Also, due to analog switch AS ₁₁ being closed,
A reference voltage +Es ₃₀ corresponding to a tube current value of, for example, 4 mA under fluoroscopic conditions is applied to the non-inverting input terminal of the error amplifier AP ₅ of the tube current control circuit. As a result, the filament heating current If supplied to the filament of the X-ray tube XT has already been preheated to the tube current (4 mA) under fluoroscopy conditions.

By the way, the tube current control circuit in FIG.
The alternating current power supply AC is converted to direct current in the direct current power supply circuit DC. That is, the AC power supply AC is rectified by a rectifier D ₂ , smoothed by a choke coil L ₃ and a capacitor C ₆ , further controlled so that the voltage reaches a set value by a transistor TR ₅ , and then connected to a resistor R ₁₈ and a capacitor C. At _{step 7} , the ripple is removed and a DC voltage is obtained.
Applied to the intermediate tap of pulse transformer _PT3 .
The voltage applied to this intermediate tap is the voltage applied to the detection resistor R ₂₁
and is applied to the inverting input terminal of the error amplifier _AP5 . The amplifier AP ₅ outputs a voltage corresponding to the difference between the detection voltage (output voltage of the DC power supply circuit DC) and the reference voltage (+Es ₃₀ in this case), and outputs a voltage corresponding to the difference between the detection voltage (output voltage of the DC power supply circuit DC) and the reference voltage (+Es 30 in this case), and outputs the voltage to the base of the transistor TR ₅ via the base resistor R ₂₉ . The voltage is controlled, the output voltage of the DC power supply circuit DC is set to a set value (voltage corresponding to the reference voltage), and as a result, the filament heating current If is set to the set value. On the other hand, each time a pulse is derived from the flip-flop FF ₁ by the output pulse of the pulse generator PG ₂ having an appropriate repetition period, the outputs "1" and "0" of the Q output terminal and the output terminal are inverted. Transistors TR ₆ , via drivers DV ₁ , DV ₂ and base resistors R ₁₉ , R ₂₀ ,
A voltage is alternately applied to the base of TR ₇ . As a result, transistors TR ₆ and TR ₇ become pulse generators.
PG turns on and off alternately with a pulse repetition period of ₂ ,
The DC power supply circuit chops the DC current to supply a rectangular wave AC current to the pulse transformer _PT3 . This rectangular wave alternating current is full-wave rectified by a rectifier D ₃ on the secondary side of the pulse transformer PT ₃ , smoothed by a capacitor C ₈ to become a direct current, and then passed through the filament of the X-ray tube XT as a filament heating current If. is supplied to.

In the above state, charge start command push button switch PS
When is pressed (B in the first diagram), the Q output terminal of the mono multivibrator MM ₂ becomes "0" (C in the first diagram) via the inverter IN ₄ , and the gate of the NOR gate NR ₃ is opened. Therefore, the pulse from the pulse generator PG ₄ is applied to the base of the transistor TR 8 via the NOR gates NR ₃ , NR ₇ , NR ₄ and _the base resistor R ₄₆ , making the transistor TR ₈ conductive. This allows the pulse transformer to be activated by the DC drive power supply +V _DD .
Current flows in pulses from the primary winding of PT ₁ (PT ₂ ) to the diode D ₁₀ to the transistor TR ₈ (collector to emitter) to ground. By deriving a pulse (L in the first diagram) from the NOR gate _NR4 , the pulse is introduced into the flip-flop _FF7 via the NOR gate _NR8 , and the output level (“1”) of the Q output terminal of the flip-flop _FF7 is
“0”) is reversed, one Noah gate NR ₄ that was open until now closes, and conversely the other Noah gate NR ₅
gate opens. Therefore, the pulses from the pulse generator PG ₄ pass through the NOR gates NR ₃ , NR ₇ , NR ₅ (first
M) in the figure and to the base of the transistor TR ₉ through the base resistor R ₄₇ , making the transistor TR ₉ conductive. As a result, the DC drive power supply +
By V _DD the primary winding of the pulse transformer PT ₂ (lower half shown) ~ diode D ₂₀ ~ transistor TR ₉
(Collector ~ Emitter) ~ Current flows in pulses with earth. By deriving a pulse from the NOR gate _NR5 , a pulse is introduced into the flip-flop _FF7 via the NOR gate _NR8 , the output level of the Q output terminal of the flip-flop _FF7 is again inverted, and said pulse is again transferred to the NOR gate NR. _Four
The operation of making transistor TR ₈ conductive via is repeated. Therefore, transistors TR ₈ , TR ₉
are alternately conducted by the output pulses of the pulse generator PG ₄ , and as a result, a high frequency rectangular wave alternating current flows through the secondary sides of the pulse transformers PT ₁ and PT ₂ .

This square wave voltage is applied to the switching control circuit SC ₂
In FIG. 2, the signal is full-wave rectified by a rectifier D ₁ and applied to the base of a transistor TR ₀ via a base resistor R ₀ . This allows the transistor
TR ₀ conducts, tetrode tube TT ₁ , (TT ₂ )
There is a short circuit between the cathode and the first gate (becomes zero potential), the tetrode tubes TT ₁ and (TT ₂ ) become conductive, and the voltage charged in the high voltage capacitors HC ₁ and HC ₂ is transferred to the tetrode tube TT _{1 .} ,X via TT ₂
Applied to the ray tube XT. Therefore, it is applied to the X-ray tube XT. Therefore, as mentioned above, from the X-ray tube XT,
A line is emitted.

When X-ray exposure begins, the high voltage capacitor
The charging voltages of HC ₁ and HC ₂ , that is, the detection voltages of the charging voltage detection resistors Rd ₁ and Rd ₂ begin to drop. On the other hand, in the charging voltage control circuit (Fig. 3), the integrator amplifier is activated at the same time as the push button switch PS is closed.
Analog switch across capacitor C ₂ of AP ₄
AS ₁ is opened and integration is started from the reference voltage Es ₁ via resistor R ₄₈ . As a result, the output of the amplifier AP ₄ gradually rises at a predetermined slope determined by the capacitor C ₁ and the resistor R ₄₈ .

Therefore, the output of the comparison operational amplifier AP ₃ is inverted from positive to negative, and the gate of the NOR gate NR ₁ opens and the oscillation pulse from the pulse generator PG ₁ is transferred to the NOR gate.
NR ₁ , transistor TR ₁ through base resistor R ₁₂
Base of or Noah Gate NR ₁ , inverter
Transistor through IN ₂ and base resistor R ₁₄
applied to the base of TR ₃ , transistor TR ₁ ,
TR ₃ conducts alternately. Therefore, DC drive power supply +
Vcc connects transistor TR ₁ (collector to emitter) ~ capacitor C ₄ ~ primary winding of pulse transformer PT ₀₁ ~ ground, then one end of capacitor C ₄ ~
Pulse currents alternately flow between the transistor TR ₃ ~ ground ~ the other end of the capacitor C ₄ . This pulse current, or rectangular wave alternating current, is a pulse transformer.
It is full-wave rectified by the rectifier D ₀₁ on the secondary side of PT ₀₁ , and is applied to the gate of the first thyristor SCR ₁ of the switching circuit SW (Fig. 2).
SCR ₁ is turned off. first thyristor
By turning off SCR ₁ , high voltage transformer HT
The neutral point of the Y-connected primary winding L ₁ is closed, and the three-phase AC power supply 3φ AC is stepped up appropriately by the high voltage transformer HT, and after full-wave rectification via the rectifiers HD ₁ and HD ₂ , the high voltage Capacitors HC ₁ and HC ₂ are charged respectively.

In this case, the high-voltage capacitors HC ₁ and HC ₂ are discharged under the aforementioned see-through conditions, but at the same time they are charged with a current larger than the discharge current. Therefore, discharge starts (fluoroscopy X-ray exposure starts)
At the same time, the integrating amplifier which is the reference voltage (charging voltage setting position) of the comparison amplifier AP ₃ (FIG. 3)
Since the output voltage of AP ₄ rises at a predetermined slope, the charging voltage of high-voltage capacitors HC ₁ and HC ₂ rises (the slope part of Figure 1 A), and the tube voltage of the X-ray tube XT increases to 60KVp.
It gradually rises from then high voltage capacitor
When the charging voltage of HC ₁ and HC ₂ reaches 120KVp, the output voltage of the integrating amplifier AP ₄ is held at 120KVp by the Zener diode ZD, so that the discharge current, that is, the detection of the detection resistors Rd ₁ and Rd ₂ Due to the voltage drop, the output voltage of the comparison amplifier AP ₃ is reversed from negative to positive. As a result, the rising level at the time of inversion gives a trigger pulse to the mono multivibrator MM ₁ via the capacitor C ₃ , the differentiating circuit of the resistor R ₁₁ and the inverter IN ₁ , and the mono multivibrator MM ₁ is activated for a predetermined pulse width. Only open the gate of Noah Gate NR ₂ . Therefore, the oscillation pulse from pulse generator PG ₁ is the NOR gate
NR ₂ is applied alternately to the base of the transistor TR ₂ via the resistor R ₁₃ or to the base of the transistor TR ₄ via the NOR gate NR ₂ , the inverter IN ₃ and the resistor R ₁₅ , and the transistor TR ₂ and the transistor TR ₄ are Conduct alternately. As a result, similar to when the transistors TR ₁ and TR ₃ are turned on, a rectangular wave alternating current is supplied to the pulse transformer PT ₀₂ , and after being full-wave rectified by the rectifier D ₀₂ on the secondary side, the 2 thyristor
given as a trigger pulse to the gate of SCR ₂ ,
Thyristor SCR ₂ turns on. By turning on this second thyristor SCR ₂ , the coil
Resonance occurs due to L ₀ and capacitor C ₀ , and a reverse bias voltage is instantaneously applied to both the first and second thyristors SCR ₁ and SCR ₂ , and both thyristors SCR ₁ and SCR ₂ are instantly turned off. do. As a result, the neutral point of the high voltage transformer HT is opened and charging of the high voltage capacitors HC ₁ and HC ₂ is stopped. However, as the X-ray exposure continues, the charging voltage of the high-voltage capacitors HC ₁ and HC ₂ drops, and then the output voltage of the comparison amplifier AP ₃ immediately reverses from positive to negative, and the NOR gate NR At the same time as the gate of NOR gate NR ₁ closes, the gate of NOR gate NR ₁ opens, and the output voltage (charging voltage) of the integrating amplifier AP ₄ increases again.
The high-voltage capacitors HC ₁ and HC ₂ are charged until the output voltage of the arithmetic unit AP ₂ (detected voltage of the charging voltage detection resistors Rd ₁ and Rd ₂ ) matches.
This operation is repeated at high speed, and a constant voltage (120 KVp) is applied to the X-ray tube XT due to the stray capacitance of the high voltage cable.

After that, when the output of the monovertical vibrator MM ₂ (Fig. 5), which is an X-ray exposure timer under fluoroscopic conditions, rises from "0" to "1" (C in the first diagram), the gate of the NOR gate NR ₃ is activated. Open pulse generator PG ₄
The oscillation pulses from the transistors TR ₉ TR _{10 are no longer supplied to the bases of the transistors TR 9 TR 10} , and as a result the transistors of the switching control circuits SC ₁ , SC ₂ (FIG. 2)
TR ₀ becomes non-conductive, and the tetrode tube TT ₁ ,
TT ₂ is cut off and X-ray exposure under fluoroscopic conditions is stopped.

At the same time that the output of the output terminal of the mono multivibrator MM ₂ rises to "1", the rising level is applied to the flip-flop via the differentiating circuit consisting of the capacitor C ₉ and the resistor R ₃₁ and the inverter IN ₅ .
FF ₂ , FF ₀ , and FF ₃ are set (D, G, H in the first diagram), and the analog switch is set.
AS ₀₂ (Figure 3) closes. As a result, flip-flop FF ₀ is set, thereby opening analog switch AS ₁₁ in the tube current control circuit (FIG. 4) and analog switch AS ₀₁ in the charging voltage control circuit (FIG. 3). At the same time, flip-flop FF ₃ is set, causing driver VD ₄
The analog switch AS ₁₂ is closed in the tube current control circuit, and the analog switch AS ₁₀ is closed in the charging voltage control circuit. Therefore, in the tube current control circuit shown in FIG. 4, the reference voltage of the error amplifier AP ₅ is switched from +E ₃₀ to E ₃₁ , and the filament heating current If is changed so that the tube current increases from 4 mA to 500 mA. is controlled. On the other hand,
In the charging voltage control circuit (Fig. 3), the reference voltage of comparison amplifier AP ₃ is switched from the output voltage of integrating amplifier AP ₄ to -Es ₂₁ , and as a result, the tube voltage is
The charging voltage is switched from 120KVp to 90KVp. In this case high voltage capacitors HC ₁ , HC ₂
is charged with a voltage of 120KVp, but since charging is kept in a stopped state, the bridge resistor Rb ₁ ,
Natural discharge occurs due to the current flowing to the ground via Rb ₂ and detection resistors Rd ₁ and Rd ₂ , and the charging voltage gradually drops. Thereafter (after about 1 minute), when the charging voltage reaches 90 KVp, the output of the comparison amplifier AP ₃ is inverted from positive to negative in the charging voltage control circuit. As a result, the flip-flop _FF2 is reset (D in the first diagram), and the rising level of its output terminal from "0" to "1" is changed by the capacitor.
Flip-flop FF ₈ is set via C ₁₅ , a differentiator circuit of resistor R ₅₁ , and inverter IN ₇ . The output from the Q output terminal causes the pulse generator PG ₃ (F in the first diagram) to start oscillating and derive pulses. This output pulse is the NOR gate NR ₇ , NR ₄ (or
NR ₅ ) and resistor R ₄₆ (or R ₄₇ ), it is applied to the transistor TR ₈ (or TR ₉ ), and is supplied to the pulse transformer PT ₁ (PT ₂ ). Pulse transformer PT ₂ transfers this pulse to the secondary side transistor.
TR ₀ (FIG. 2) is applied to the base of the pulse, and the tetrode tube TT ₁ (TT ₂ ) is made conductive for a period of the pulse width. At the same time, the output pulses of the pulse generator _PG3 are counted by the counter CT, and when two pulses are counted, the "2" output terminal of the decoder DD changes from "1" to "0", and the flip-flop _FF4 is set (as shown in Figure 1). H) Do. Therefore, from the X-ray tube XT,
Two pulsed X-rays under the same conditions (500mA-90KVp)
Once exposed, the exposure conditions are switched. That is, when the flip-flop FF ₄ is set (I in the first diagram), the analog switch AS ₁₂ is opened in the tube current control circuit (FIG. 4) via the driver DV ₅ , and the analog switch AS ₁₃ is closed, and the charging voltage control circuit is also controlled. In the circuit (Fig. 3), analog switch AS ₁₀ opens, analog switch AS ₂₀ closes,
As a result, the tube current is changed to 400mA and the tube voltage is changed to 100KVp. When X-rays are irradiated twice again under these conditions, the counter CT counts two more pulses, the "4" output terminal of the decoder DD changes from "1" to "0", and the flip-flop FF ₄ ( I) in the first diagram is reset, flip-flop FF ₅ is set (J in the first diagram), and similarly, when the counter CT counts six pulses, the flip-flop
FF ₅ is reset (J in the first diagram), flip-flop FF ₆ is set (K in the first diagram), and if eight more shots are counted, flip-flop FF ₆ is reset (J in the first diagram).
(K) shown in the diagram. As a result, in the tube current control circuit, the open/closed states of the analog switches AS ₁₃ to AS ₁₅ , that is, the reference voltage of the error amplifier AP ₅ + Es ₃₂ to
+Es ₃₄ is switched sequentially, tube current is 400mA ~ 375m
Filament heating current to A~350mA
If is controlled. In addition, in the charging voltage control circuit, the open/close status of analog switches AS ₂₀ to AS ₄₀ ,
That is, the reference voltage of comparison amplifier AP ₃ −Es ₂₂ ~−
Es ₂₄ is switched sequentially and the tube voltage is 100KVp ~
High voltage capacitor to be 110KVp~120KVp
The charging voltage of HC ₁ and HC ₂ is controlled. counter
When the CT counts 8 pulses, that is, the pulse X-ray is irradiated 8 times, the counter CT is cleared and the flip-flops FF ₈ , FF ₆ , and FF ₀ are reset, so that the oscillation of the pulse generator PG ₃ stops. The analog switches AS ₁₅ and AS ₄₀ are opened, and the analog switches AS ₁₁ and AS ₀₂ are closed to return to the initial state. Flipflop FF ₁₀ at the same time
is set, the lamp LM lights up (or the buzzer sounds) via the driver gate NG ₂ , notifying the operator that aging has ended, and sending an X-ray photography enable signal to the X-ray controller (not shown). Release the interlock that prohibits exposure to X-rays. The flip-flop FF ₁₀ is reset automatically after a certain period of time or by the operator.

As described above, according to the present invention, the aging of the X-ray tube for pulsed X-ray generation is always performed automatically according to the appropriate program, so that it is possible to avoid the possibility of aging due to a mistake in setting aging conditions or forgetting to perform aging. Damage to the X-ray tube can be prevented.

The present invention is not limited to the above-mentioned embodiment; in the above-mentioned embodiment, the voltage charged in the high-voltage capacitor provided on the secondary side of the high-voltage transformer is applied to the X-ray tube, and the voltage applied to the high-voltage capacitor is We have described a method for arbitrarily setting the tube voltage by controlling the charging voltage, but there is a general method that does not use a high-voltage capacitor and arbitrarily sets the tube voltage by controlling the voltage on the primary side of the high-voltage transformer. Of course, this can also be applied. in this case,
Instead of the charging voltage control circuit described above, the primary side voltage control circuit of the high voltage transformer may be configured using a known technique. It goes without saying that other modifications may be made as appropriate without changing the gist.

[Brief explanation of drawings]

FIG. 1 is a signal waveform diagram for explaining the operation of the automatic aging device according to the present invention, FIG. 2 is an electric circuit diagram showing an embodiment of the high voltage generation circuit of the automatic aging device according to the present invention, and FIG. 2 is an electric circuit diagram showing an example of the charging voltage control circuit for the high-voltage capacitor, and FIG.
An electric circuit diagram showing one embodiment of a tube current (filament heating current) control circuit for a wire tube, FIG. 5 shows the charging voltage control circuit, the tube current control circuit, and the tetrode tube switching control circuit of FIG. FIG. 3 is an electrical circuit diagram showing an example of a circuit that provides control signals. HT...High voltage transformer, HC ₁ , HC ₂ ...High voltage capacitor, Rd ₁ , Rd ₂ ...Charging voltage detection resistor,
TT ₁ , TT ₂ ...Tetrode tube, SC ₁ , SC ₂
...Switching control circuit, XT...X-ray tube,
SW...Switching circuit, AP ₁ to _{AP 5} ...Operation amplifier, MM ₁ , MM ₂ ...Mono multivibrator, FF ₁ to FF ₁₀ ...Flip-flop, NR ₁ to
NR ₈ ...Nor gate, PG ₁ ~ _{PG 4} ...Pulse generator, CT...Counter, DD...Decoder, TR ₁ ~
TR ₈ ...transistor, PT ₁ , PT ₂ , PT ₀₁ ,
PT ₀₂ , PT ₃ ... Pulse transformer, AS ₀₁ , AS ₀₂ ,
AS ₁₁ ~ AS ₁₅ , AS ₁₀ ~ AS ₄₀ ...Analog switch, LM...Lamp.

Claims (1)

[Scope of Claims] 1. Voltage control means capable of outputting a plurality of predetermined types of voltage values; Current control means capable of outputting a plurality of predetermined types of current values; and the voltage control device. control signal generating means for selecting and outputting values that can be outputted from the means and the current controlling means one by one in a predetermined order and timing; and the voltage controlling means according to the control of the control signal generating means. and X-ray exposure means for emitting X-rays according to the conditions output from the current control means. 2. The X-ray exposure means includes a high-voltage transformer and an X-ray tube, and the voltage control means is provided on the secondary side of the high-voltage transformer and applies charging pressure to the X-ray tube via a switching element. 2. The automatic aging device according to claim 1, comprising a high voltage capacitor and a charging voltage control circuit for controlling charging voltage of the high voltage capacitor. 3. Claim 1 or 2, characterized in that the control signal generating means outputs a termination signal when the control of the tube voltage and tube current based on the predetermined order and timing is completed.
Automatic aging device as described in section. 4. A patent claim characterized in that the predetermined order and timing are determined such that X-rays are intermittently irradiated by switching a plurality of combinations of tube voltage and tube current in stages. The automatic aging device according to any one of the ranges 1 to 3. 5. The automatic aging device according to claim 4, wherein the predetermined order and timing include a pattern in which the same combination of tube voltage and tube current conditions is repeated at least twice.