JP4662518B2 - X-ray high voltage device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray generation power supply device for medical use or industrial use, and the voltage between the anode and the cathode of the X-ray tube (hereinafter referred to as tube voltage) during a period in which X-ray emission from the X-ray tube is stopped. Is reduced at a high speed, the error between the set imaging time and the actual imaging time is always reduced regardless of the current flowing between the anode and cathode of the X-ray tube (hereinafter referred to as tube current). In addition, the present invention relates to an X-ray high voltage apparatus that can prevent generation of soft X-rays.
[0002]
[Prior art]
Conventionally, an apparatus for controlling the tube voltage of an X-ray high voltage apparatus at high speed has been developed. In these X-ray high-voltage devices, the AC high-voltage output of a high-voltage transformer is usually rectified by a high-voltage rectifier, and this is added to the high-voltage side or a capacitor such as a stray capacitance of a high-voltage cable. The DC high voltage is supplied to the X-ray tube after smoothing.
[0003]
In this case, since there is a high voltage rectifier, the discharge of the electric charge stored in the capacitor has only a route via the X-ray tube, so it is relatively easy to start up the tube voltage at a high speed. There is a technical problem that it is difficult to descend the vehicle at high speed.
[0004]
For this reason, a high-speed pulsed tube voltage is required, such as cine imaging in which blood flow in a blood vessel is imaged on a cine film, and pulse fluoroscopy to obtain a high-quality real-time image when operating a catheter in a blood vessel. In the X-ray high voltage apparatus, a waveform when the tube voltage drops (hereinafter referred to as a wave tail) becomes a problem. That is, this wave tail has little effect on X-ray images formed on an X-ray film or an X-ray television, and in addition, a large amount of low-energy X-rays that are likely to be harmful exposure to the subject from the X-ray tube. Will be emitted. In particular, this effect is hindered by the phenomenon of ineffective exposure to medical practices under high-quality fluoroscopy represented by interventional radiology.
[0005]
Further, during the wave tail period of the tube voltage, the electric power stored in the capacitor in the X-ray tube is consumed, so that the internal temperature of the X-ray tube is increased accordingly, the life of the tube is shortened, and the pulse X Problems such as restricting the allowable X-ray conditions after line output occur.
[0006]
As one method for solving such a problem, there is a method of shortening the wave tail by short-circuiting the anode and the cathode using a tetrode (quadrupole vacuum tube) (Japanese Patent Laid-Open No. 51-6669). However, in this method, the tetrode is large, which prevents the miniaturization of the X-ray high-voltage device, and the tetrode itself is expensive and, in addition, is a consumable part, so it needs to be replaced periodically. Is also disadvantageous. Therefore, as a method for solving this problem, a series connection body of a current limiting impedance and a high voltage switch is provided between the anode and cathode of the X-ray tube, and the charge accumulated in the capacitor on the high voltage side is discharged at high speed. A device (hereinafter referred to as a tube voltage wave tail cutting device and a circuit used for this device is referred to as a wave tail cutting circuit) is disclosed in Japanese Patent Application Laid-Open No. 8-212948. In this method, a plurality of power semiconductor switching elements (hereinafter referred to as semiconductor switches) are connected in series, and a series connection body of a high voltage switch for sequentially switching these semiconductor switches and a current limiting impedance is parallel to the capacitor. And when the X-ray emission is stopped, the high-voltage switch is switched to rapidly discharge the charge accumulated in the capacitor, thereby rapidly lowering the tube voltage.
[0007]
[Problems to be solved by the invention]
However, in the tube voltage wave cutting device using a high voltage switch in which a plurality of conventional semiconductor switches are connected in series, in the case of a failure in which some of the plurality of semiconductor switches are short-circuited due to some cause It is conceivable that the shared voltage of other semiconductor switches that have been operating normally becomes unbalanced and an overvoltage higher than the rated voltage of the switch is applied to the semiconductor switch.
[0008]
In such a case, there is a concern that other semiconductor switches other than the above-mentioned failure may be destroyed in a chain, and if this happens, the high-voltage semiconductor switch is always in a conductive state. The impedance for current limiting is always connected in parallel with the tube, and the load impedance of the high voltage transformer is reduced. For this reason, the tube voltage applied to the X-ray tube becomes a set value or less. In particular, an inverter type X-ray that converts a DC voltage to a frequency higher than the commercial power supply frequency using an inverter circuit, boosts this high-frequency AC voltage with a high-voltage transformer, rectifies it, and applies it to the X-ray tube In the high voltage device, the tube voltage applied to the X-ray tube is detected and feedback control is performed so that the tube voltage becomes a target value. Therefore, the tube voltage is set due to a short circuit failure of the tube voltage wave cutting device. When the value becomes lower than the value, the inverter circuit operates so as to reach the target voltage by the feedback control operation, so that the output current of the inverter circuit increases. This inverter circuit is also composed of a semiconductor switch. When the current of the inverter circuit increases, an overcurrent flows through the semiconductor switch, the inverter circuit also breaks down and loses its function as an X-ray high voltage device. It can be.
[0009]
On the other hand, if the semiconductor switch fails such that it is in an open state, the charge charged in the capacitor on the high voltage side cannot be discharged, and the wave tail of the tube voltage cannot be cut off.
However, in the case of such a failure, it is only impossible to cut the wave tail of the tube voltage, but the operator is not aware that the wave tail is not cut, and as a result, the subject or the operation Increase of the person's ineffective X-ray exposure and increase in the loss of the X-ray tube.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tube voltage wave tail cutting device that discharges the charge of a capacitor connected in parallel with an X-ray tube when X-ray emission is stopped to drop the voltage between the anode and cathode of the X-ray tube at high speed. X is designed to improve safety and reliability by detecting the failure of the high voltage switch of the X-ray, releasing the parallel connection between the tube voltage tail cutting device and the capacitor and displaying or notifying the failure. It is to provide a line high voltage device.
[0011]
[Means for Solving the Problems]
The purpose is to provide an AC voltage source, a high voltage transformer to which the primary winding is connected to the AC voltage source and boost the voltage, and a boosted AC voltage connected to the secondary winding of the high voltage transformer. A high voltage rectifier for converting to a DC high voltage, a capacitor connected to the high voltage rectifier and smoothing the DC high voltage, an X-ray tube connected to the capacitor, and a high voltage semiconductor connected in parallel with the capacitor A series connection body of a switch and a current limiting impedance, and high voltage semiconductor switch drive control means for driving and controlling the high voltage semiconductor switch to be conductive or nonconductive, and stop emission of X-rays from the X-ray tube In the X-ray high-voltage apparatus, the high-voltage semiconductor switch drive control means conducts the high-voltage semiconductor switch during a period to discharge the capacitor. A high voltage semiconductor switch failure detecting means for detecting a failure of the conductor switch, the series connection in the detection signal detected by the failure detection means is achieved by providing a means for disconnecting from said condenser.
[0012]
By configuring in this way, the high-voltage semiconductor switch failure detecting means detects a short-circuit or open-circuit failure of the high-voltage semiconductor switch, and this means operates the means for disconnecting the series connection body from the capacitor. The high-voltage semiconductor switch is disconnected from the capacitor, and the X-ray tube from the X-ray tube comprises a series connection of a high-voltage semiconductor switch and a current-limiting impedance connected in parallel with the capacitor and high-voltage semiconductor switch drive control means. The X-ray high-voltage device is protected by preventing a failure that affects other than the wave-tail cutting circuit that discharges the charge of the capacitor during the period in which the radiation of the line is stopped. A mechanical switch may be used as a means for separating the series connection body from the capacitor, but a high-speed response cutoff function is possible by adopting a switch configuration including a power semiconductor switching element. Become.
[0013]
Further, according to the present invention, a countermeasure can be quickly taken by displaying or notifying the failure of the high voltage semiconductor switch by the detection signal of the high voltage semiconductor switch failure detecting means. Thus, in the present invention, the failure of the X-ray high-voltage apparatus, which is caused by the failure of the wave tail cutting circuit, can be prevented, and the increase in the invalid X-ray exposure of the subject and the operator and the loss of the X-ray tube can be prevented. This is intended to improve the safety and reliability of an X-ray high-voltage apparatus having a wave tail cutting function.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment in which the present invention is applied to an inverter type X-ray high voltage apparatus.
1 is a DC power source, 2 is an inverter circuit that converts the DC voltage of the power source 1 into an AC voltage having a high frequency (hereinafter abbreviated as high frequency), and 3 is a high voltage that is connected to the inverter circuit 2 and boosts the high-frequency AC voltage. A voltage transformer 4 is connected to the secondary side of the high voltage transformer 3 to rectify the boosted AC voltage, and 5 is connected to the high voltage rectifier 4 to smooth the output voltage. The capacitance is composed of a floating capacitance of a high voltage cable 6 that connects the high voltage rectifier 4 and the X-ray tube described below, and a smoothing high voltage capacitor that is added as necessary. 7 is an X-ray tube connected to the smoothing capacitance 5, 11 is a control circuit for controlling tube voltage, tube current, etc. for controlling the X-ray dose radiated from the X-ray tube 7, and 17 is an imaging condition. And an operation console that sets various commands and gives target values (set values) such as tube voltage and tube current to the control circuit 11. Reference numeral 12 denotes a wave tail cutting circuit, which comprises a series connection circuit of a high voltage switch 8 and a current limiting resistor 9 and a switch drive circuit 10 for driving the high voltage switch 8. A high voltage switching switch 13 is provided in series with the series connection body with the current limiting impedance 9, and these series connection bodies are connected in parallel with the smoothing capacitance 5, and the charge of the smoothing capacitance 5 Is formed when the X-ray emission is stopped, and a circuit having a tube voltage wave tail cutting function for rapidly dropping the voltage between the anode and the cathode of the X-ray tube is constructed. The present invention protects the high voltage switch 8 by disconnecting the high voltage switch 8 from the high voltage generator 18 during abnormal operation due to a failure of the high voltage switch 8 of the wave tail cutting circuit 12, and so on. Is a switch for this.
[0015]
That is, failure detection of the high voltage switch 8 is performed, and a signal for opening the high voltage switching switch 13 is output from the high voltage switching switch driving circuit 14 by this signal to control the opening and closing of the high voltage switching switch 13.
[0016]
In the above inverter type X-ray high voltage apparatus, 18 circuit parts surrounded by dotted lines such as the high voltage transformer 3, the high voltage rectifier 4 and the wave tail cutting circuit 12 are applied with a high voltage. In order to ensure the voltage, for example, it is integrally stored in a tank filled with insulating oil.
[0017]
FIG. 2 shows the configuration of the high-voltage switch 8 and the specific configuration of the high-voltage switch driving circuit 14 that detects the failure of the high-voltage switch and controls the opening / closing of the switch 13 for switching the high-voltage using this detection signal. An example is shown.
[0018]
Series connection body 2 of power semiconductor switching elements constituting the high voltage switch 8 ₁ ~ 2 _n Is an arbitrary number of a plurality of power semiconductor switching elements corresponding to the withstand voltage between the anode and cathode of the X-ray tube 7 connected in series.
[0019]
The power semiconductor switching element shown in FIG. ₂₁₁ To Q _21n Are connected in series to withstand a predetermined voltage. Each MOSFET has a resistance R for improving the transient characteristics in order to reduce the unbalance of the transient voltage at the turn-on and turn-off of these MOSFETs. ₁ ~ R _n And capacitor C ₁ ~ C _n Series connection body of Zener diode ZD _{twenty one} ~ ZD _2n In order to prevent an overvoltage from being applied between the gate and source of each MOSFET, a Zener diode ZD1 is connected. ₁ ~ ZD1 _n Are connected in parallel. The MOSFETQ in the front row of the series connection body of MOSFETs in FIG. ₂₁₁ Gate G ₁ And source S ₁ When a drive voltage from the drive circuit 10 in FIG. ₂₁₁ Is conductive and capacitor C ₁ The voltage charged in the resistor R ₁ Q of the next stage through ₂₁₂ Q is charged between the gate and the source of the transistor and when this reaches a predetermined voltage, the Q ₂₁₂ Are conducted, and the MOSFETs are successively conducted thereafter, so that the last MOSFET Q21 _n Is conducted, and the switching of the high voltage switch 8 is completed. A signal for driving the MOSFET is generated by the control circuit 11, and when the X-ray exposure is stopped, the signal is amplified by the drive circuit 10 and applied to the gate of each MOSFET to perform the switching operation of the MOSFET.
[0020]
[1] High voltage switch circuit failure detection and equipment protection
(1) High voltage switch circuit failure detection
2 in FIG. 2 is a semiconductor switching element of the high-voltage switch 8, here MOSFETQ. ₂₁₁ To Q21 _n It is a circuit which detects the failure which becomes a short circuit state and open state of.
1) Detection of short-circuit state of semiconductor switching element
As described above, a plurality of semiconductor switching elements are connected in series and share an applied voltage.
[0021]
When the semiconductor switching element is in an open state, that is, when the wave voltage cutting operation (discharge operation of the high voltage capacitor 5) of the tube voltage is not performed, the semiconductor is compared with the impedance value (100 kΩ to several hundred kΩ) of the current limiting impedance 9. Since the impedance value of the switching element 11 is sufficiently large as several MΩ, tube voltages are applied almost uniformly to the semiconductor switching elements connected in series.
[0022]
At this time, if the value of the voltage applied to one semiconductor switching element is X (V) and the rated voltage Y (V) of the semiconductor switching element, Y> X is satisfied and the rated voltage of the semiconductor switching element is satisfied. The semiconductor switching element is selected so that a sufficient margin can be obtained.
[0023]
However, when some of the semiconductor switching elements are short-circuited, the voltage sharing balance of the plurality of semiconductor switching elements is broken, and the tube voltage is applied to other semiconductor switching elements that are not short-circuited. When a voltage higher than that before the short-circuit failure is applied to the remaining semiconductor switching elements that have not caused the short-circuit failure, and the value of this voltage is Z (V), the relationship is Z> X. In this way, when a short circuit failure occurs and Z> Y, that is, when a voltage higher than the rated voltage of the element is applied to the semiconductor switching element, the remaining semiconductor switching elements not causing the short circuit failure are also damaged in a chain. To do. In this case, it is conceivable that almost all will cause a short circuit failure.
[0024]
The comparison circuit 15a of the high voltage changeover switch drive circuit 14 in FIG. 2 is a circuit that detects the short-circuit state.
A reference value 1 of Y or a value smaller than Y is input to the comparison circuit 15a in advance, and the reference value 1 and, for example, the semiconductor switching element Q21 are input. _n The comparison circuit 15a compares the voltage applied to the output voltage and outputs a signal from the comparison circuit 15a when X becomes larger than the reference value 1 to detect a short circuit failure of the semiconductor switching element.
[0025]
As described above, since the tube voltage is applied to the semiconductor switching elements almost equally, it is only necessary to monitor the voltage of at least one of the semiconductor switching elements connected in series.
In addition, the failure which will be in a short circuit state may cause the semiconductor switching element to monitor to be in a short circuit state. In this case, since X = 0, a reference value 2 larger than 0 is prepared for the switch drive circuit 14, and this is compared with the voltage of the semiconductor switching element by the comparison circuit 15b. Detects a short-circuit failure.
[0026]
2) Detection of open state of semiconductor switching element
During the operation of the high voltage switch at the time of wave tail disconnection, for example, if one switching element of the high voltage switch becomes a failure in an open state, the voltage sharing balance between the elements is lost as described above. The reference values of the comparison circuits 15a and 15b can be set to a value corresponding to an open circuit fault and can be detected by the same method as in the case of the short circuit fault.
[0027]
(2) Protection of equipment in case of high voltage switch circuit failure
1) Device protection in case of short circuit failure
As described above, when the semiconductor switching element of the high voltage switch circuit is short-circuited, the current limiting impedance is always connected in parallel with the X-ray tube, and the load impedance of the high voltage transformer is reduced. For this reason, the tube voltage applied to the X-ray tube is lower than the set value. In particular, in the inverter type X-ray high voltage apparatus, the tube voltage applied to the X-ray tube is detected and becomes the target value. Therefore, when the tube voltage becomes lower than a set value due to a short circuit failure of the high voltage switch 8, the inverter circuit operates so as to reach the target voltage by the feedback control operation. The output current of the circuit increases. This inverter circuit is also composed of a semiconductor switch. When the current of the inverter circuit increases, an overcurrent flows through the semiconductor switch, the inverter circuit also breaks down and loses its function as an X-ray high voltage device. It can be.
[0028]
Therefore, in order to prevent such a secondary failure, in the present invention, in the case of the failure, the high voltage switch 13 is opened to disconnect the high voltage switch 8 from the high voltage generator 18. . Specifically, the output signals of the comparison circuits 15a and 15b of the high voltage changeover switch drive circuit 14 shown in FIG. 2 are amplified by the amplifier circuit 15c, and the high voltage changeover switch 13 is opened by these signals to increase the high voltage. The voltage switch 8 is disconnected from the circuit.
[0029]
At this time, the opening signal is sent to the console 17, and the operator is notified by taking measures such as indicating that the high voltage switch 8 is short-circuited on the display on the console 17 or sounding an alarm. If you do, you will be able to take quick measures.
[0030]
2) Device protection in case of open failure
At the time of this failure, as in the case of the short-circuit failure, the high-voltage switch 13 is opened to disconnect the high-voltage switch 8 from the high-voltage generator 18, and the high-voltage switch 8 is displayed as an open failure. Then, take measures such as sounding an alarm to notify the operator.
[0031]
[2] Method of detecting failure from measured values of each part of X-ray high-voltage device and protection of device As described above, the voltage, current, etc. of each part of the device can be detected without directly detecting the failure of the high-voltage switch circuit. A failure of the high voltage switch circuit can be detected from the measured value. That is, the failure of the high voltage switch circuit can be detected by monitoring the values of the tube voltage, the X-ray dose, the current of the inverter circuit, etc. during the operation of the X-ray high voltage apparatus and the wave tail cutting circuit. it can.
[0032]
(1) Detection based on tube voltage time width
The tube voltage is fed back to the control circuit 11, and the control circuit 11 constantly monitors whether a tube voltage value according to the target value is applied to the X-ray tube. If the tube voltage value is lower than the target value, the control circuit 11 increases the tube voltage, and if the tube voltage value is higher than the target value, the control circuit 11 operates to decrease the tube voltage.
[0033]
When the semiconductor switching element is in the open state, the wave tail is not cut, so the tube voltage waveform feedback-controlled by the control circuit 11 has a long wave tail, and the pulse width setting of the tube voltage set by the console 17 is performed. The time of the tube voltage waveform becomes longer than the time by the amount of the wave tail.
[0034]
When the set pulse width time of the tube voltage is T (seconds), if the tube voltage value that is feedback-controlled in the time T + ΔT is greater than 0, the wave tail cutting is not performed. Therefore, this is judged by the control circuit 11, and thereby an open failure state of the semiconductor switching element is detected.
[0035]
FIG. 3 is a specific circuit diagram of the above method, and FIG. 4 is a detection timing chart of the open state.
The circuit of FIG. 3 compares a tube voltage detector 21 that detects a tube voltage with a detection voltage of the tube voltage detector 21 and a target (set) tube voltage 22 and controls them so that they match. 11 and a counter 23 for measuring the X-ray exposure time and measuring the wave tail of the tube voltage described later.
[0036]
Normally, the control circuit 11 for controlling the tube voltage supplies a drive control signal 24 for driving the semiconductor switching element of the circuit to the inverter circuit 2 so that the voltage detected by the tube voltage detector 21 matches the target voltage 22. Output.
[0037]
When the tube voltage is lowered at high speed as in the case of pulse fluoroscopy, the target (setting) tube voltage 22 becomes 0 and simultaneously this signal is sent to the wave tail cutting circuit 12, and the wave tail is cut by this signal. At the time of failure of the wave tail cutting circuit 12, even if the target (set) voltage becomes 0, the actual tube voltage (output voltage of the voltage divider 21) has a wave tail for a while. By detecting the presence of the wave tail, the abnormality of the wave tail cutting circuit 12 can be detected.
[0038]
That is, in FIG. 3, the output voltage 21 of the tube voltage detector and the target voltage 22 are input to the counter 23, and the output voltage 21 of the tube voltage detector remains at a predetermined value even if the target voltage 22 becomes 0 and a predetermined time elapses. If it does not drop to, the wave tail cutting circuit 12 is regarded as a failure. Specifically, as shown in FIG. 4, the counter 23 measures the wave tail of the tube voltage from the detection timing, and the output of the tube voltage detector is output even when the target voltage 22 becomes 0 and a predetermined time elapses. If the voltage 21 has not dropped to a predetermined value, the wave-tail cutting circuit is regarded as a failure, and a failure signal 25 is sent from the counter 23. Then, this signal is given to the high voltage changeover switch drive circuit 14 shown in FIG. 1 to open the high voltage changeover switch 13 and disconnect the wave tail cutting circuit 12 from the circuit.
At this time, the failure signal 25 is also sent to the console 17, and the operator is displayed on the display on the console 17 to indicate that the wave tail cutting circuit 12 is faulty or to sound an alarm. Let them know.
[0039]
(2) Detected from the output current of the inverter circuit
When the high-voltage switch circuit 8 fails in a short-circuit state, the current limiting impedance 9 is connected in parallel with the X-ray tube 7 and the load on the inverter circuit 2 increases, so that the output current of the inverter circuit 2 operates normally. Therefore, the short-circuit fault of the high voltage switch 8 can be detected by monitoring the magnitude of the current.
[0040]
FIG. 5 is a specific circuit diagram for detecting a short-circuit fault of the high voltage switch 8 by monitoring the output current of the inverter circuit 2. In this figure, 31 is a current detector for detecting the output current of the inverter circuit 2, and the current value detected by this current detector is converted into a voltage by the voltage converter 32, and this and the inverter circuit 2 during normal operation are converted. The comparison voltage output from the comparison voltage generation circuit 33 corresponding to the output current is compared by the comparison circuit 34. When the output voltage of the voltage converter 32 is larger than the output voltage of the comparison voltage generation circuit 33, the comparison circuit 34 Further, a failure signal 35 is outputted, and this signal is given to the high voltage changeover switch drive circuit 14 shown in FIG. 1 to open the high voltage changeover switch 13 and disconnect the high voltage switch 8 from the circuit.
At this time, a failure signal 35 is also sent to the console 17, and the operator is indicated on the display on the console 17 to indicate that the wave tail cutting circuit 12 is malfunctioning or to sound an alarm. Inform.
[0041]
(3) Detection from radiation X-ray output from X-ray tube
When used in a wave tail cutting mode, such as during pulse fluoroscopy, if the high voltage switch 8 fails in the open state, the wave tail of the tube voltage will not be cut, so X-ray radiation from the X-ray tube Since the X-ray dose radiated from the X-ray tube during the period of stopping the wave is larger than that at the time of wave tail cutting, it is possible to detect an open failure of the high voltage switch 8 of the wave tail cutting circuit 12 by detecting this. .
[0042]
Specifically, the X-ray dose detector and the fluorescence amount detector measure the radiation X-ray dose and fluorescence amount from the X-ray tube, and compare these with a reference value to detect the failure. The detected signal is applied to the high voltage changeover switch drive circuit 14 shown in FIG. 1 to open the high voltage changeover switch 13 and disconnect the high voltage switch 8 from the circuit.
At this time, the failure signal is also sent to the console 17, and the operator is indicated on the display on the console 17 to indicate that the wave tail cutting circuit 12 is faulty or to sound an alarm. Inform.
[0043]
As described above, the function of detecting the failure of the wave tail cutting circuit 12 and disconnecting the high voltage switch 8 of the wave tail cutting circuit from the high voltage generating circuit 18 of the X-ray high voltage device to protect the X-ray high voltage device is an inverter. Although the example used for the formula X-ray high voltage apparatus has been described, it goes without saying that the present invention can be applied to other X-ray high voltage apparatuses other than the inverter type X-ray high voltage apparatus. Further, the means for detecting the failure of the wave tail cutting circuit 12 is not limited to the above embodiment, and any means can be used as long as it can detect the failure of the wave tail cutting circuit 12. In addition, a failure detection signal of the wave tail cutting circuit 12 is sent to the console 17 so that a display on the console 17 indicates that the wave tail cutting circuit 12 is faulty or an alarm is sounded. However, this may be provided in the examination room 7 other than the operation room. This is particularly effective when the operator is positioned immediately next to the subject, such as during catheter manipulation.
[0044]
【The invention's effect】
As described above, according to the present invention, an error between the set imaging time and the actual imaging time is always reduced regardless of the tube current by reducing the tube voltage at high speed during the period in which the X-ray emission from the X-ray tube is stopped. In an X-ray high voltage apparatus provided with wave tail cutting means for reducing the size and preventing generation of soft X-rays, this is detected when the wave tail cutting means fails and the wave tail cutting means is detected. Since the cutting means is separated from the high voltage generating unit of the X-ray high voltage device and the failure is displayed or notified, the failure of the X-ray high voltage device caused by the failure of the wave tail cutting means, and the subject, It is possible to prevent an increase in the operator's ineffective X-ray exposure, an increase in the loss of the X-ray tube, and the like, and it is possible to improve the safety and reliability of the X-ray high voltage apparatus having the wave tail cutting function. .
[Brief description of the drawings]
FIG. 1 is a diagram showing an example in which the present invention is applied to an inverter type X-ray high voltage apparatus.
FIG. 2 is a diagram showing a specific configuration of the high voltage switch of FIG. 1 and a high voltage changeover switch driving circuit having a failure detection function of the high voltage switch.
FIG. 3 is a diagram showing a specific configuration of a circuit for detecting a failure of a high voltage switch from a tube voltage waveform.
4 is a timing diagram of the circuit of FIG.
FIG. 5 is a diagram showing a specific configuration of a circuit for detecting a failure of a high voltage switch from an output current of an inverter circuit.
[Explanation of symbols]
2 ... inverter circuit, 3 ... high voltage transformer, 4 ... high voltage rectifier, 5 ... smoothing capacitor, 6 ... high voltage cable, 7 ... x-ray tube, 8 ... high voltage switch, 9 ... current limiting impedance, 10 ... high Voltage switch drive circuit, 11 ... control circuit, 12 ... wave tail cutting circuit, 13 ... high voltage switching switch, 14 ... high voltage switching switch drive circuit, 17 ... console

Claims (2)

An AC voltage source, a high voltage transformer connected to the AC voltage source with a primary winding to boost the voltage, and a boosted AC voltage connected to the secondary winding of the high voltage transformer to a DC high voltage A high-voltage rectifier for conversion, a capacitor connected to the high-voltage rectifier and smoothing the DC high voltage, an X-ray tube connected to the capacitor, a high-voltage semiconductor switch connected in parallel with the capacitor, and a current limiter A series connection body with impedance, and high voltage semiconductor switch drive control means for driving and controlling the high voltage semiconductor switch to be conductive or nonconductive, and the high voltage semiconductor switch is controlled during a period in which X-ray emission from the X-ray tube is stopped. In the X-ray high voltage apparatus in which the high voltage semiconductor switch is turned on by the voltage semiconductor switch drive control means to discharge the capacitor, the high voltage semiconductor switch A high voltage semiconductor switch failure detecting means for detecting a fault, X-rays high voltage apparatus, characterized in that a means for separating the series connection in the detection signal detected by the failure detecting means from the capacitor. 2. The X-ray high voltage apparatus according to claim 1, further comprising means for displaying or notifying a failure of the high voltage semiconductor switch by a detection signal of the high voltage semiconductor switch failure detection means.

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