JP5891069B2 - X-ray equipment - Google Patents

Description

  The present invention relates to an X-ray apparatus, and more particularly to control of a rotary anode X-ray tube.

An anode of a rotary anode type X-ray tube used in an X-ray apparatus is composed of a rotor and an umbrella-shaped target, and rotates on the principle of an induction motor. By rotating the target (rotating anode), the electron impact area of the target increases, and in the case of a short time load, the input per unit area of the focal point can be greatly increased, realizing a large-capacity X-ray tube It can be done.
In a conventional X-ray apparatus using a rotary anode X-ray tube, an alternating voltage is applied to drive an induction motor during general imaging, and the rotational speed is increased to about 180 Hz, for example. After imaging is completed, a DC voltage is applied to the anode side stator, and the induction motor on the anode side of the X-ray tube is stopped. This is because if the rotating anode is left without applying a DC voltage, the rotating speed of the anode passes through the resonance frequency when the rotating speed decreases from the high speed rotation at the time of photographing, and at this time, resonance occurs in the rotating anode. This is because the bearing of the tube may be damaged.
In order to prevent this, conventionally, when photographing is finished, a DC voltage is applied to the rotating anode, and a frequency in the vicinity of the resonance frequency is passed in as short a time as possible.

JP 2001-76895 A

  However, as described above, if a DC voltage is applied after the shooting is completed and the rotation of the rotating anode is stopped, it is necessary to rotate the rotation anode again to a predetermined high speed when moving to the next shooting. It took a lot of time to become.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to control the number of revolutions of the anode so that it can quickly respond to the next operation while avoiding resonance of the rotating anode. An X-ray apparatus and a control method thereof are provided.

In order to achieve the above-described object, the present invention is an X-ray apparatus having a rotary anode type X-ray tube apparatus, wherein an AC voltage is applied to a stator coil when driving the rotary anode, When braking the rotating anode, a DC voltage is applied, and when the rotating anode is operated in inertia, a starter unit that stops the application of voltage, a control unit that controls the starter unit, and photographing is finished and the The estimated arrival time from when the rotating anode starts the inertia operation until the rotational speed of the rotating anode reaches the vicinity of the resonance frequency of the X-ray tube apparatus, and the imaging after the imaging is completed, the rotating anode performs the inertia operation. A storage unit that stores in advance an estimated passage time from when the rotation anode rotates until the rotation frequency of the rotary anode passes through the vicinity of the resonance frequency of the X-ray tube device ; Is finished, the rotating anode Wherein is overrun condition, further, during the shooting is completed by counting the elapsed time from the rotating anode is started the overrun condition, from the elapsed time the estimated arrival time to the estimated transit time, the rotary anode The X-ray apparatus is characterized in that the system is braked.

  According to the present invention, it is possible to provide an X-ray apparatus capable of controlling the number of rotations of the anode so that the next operation can be quickly handled while avoiding resonance of the rotating anode.

1 is an overall configuration diagram of an X-ray apparatus 1 according to a first embodiment. The flowchart for demonstrating the control action of 1st Embodiment The figure which shows transition of the rotation speed of the rotating anode 20 after completion | finish of general imaging | photography. The figure which shows transition of the rotation speed of the rotating anode 20 in the case of starting general imaging again after completion of general imaging Overall configuration diagram of the X-ray apparatus 2 of the second embodiment Flowchart for explaining the control operation of the second embodiment The figure which shows the transition of the actual elapsed time t after completion | finish of imaging | photography, the transition of the rotation speed of the rotating anode 20, and the timing which instruct | indicates the drive of a rotating anode 20, inertia, and braking.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, the configuration of the X-ray apparatus 1 according to the first embodiment will be described with reference to FIG.

As shown in FIG. 1, an X-ray apparatus 1 of the present invention includes an AC power supply 11, a diode module 12, a boost chopper circuit 13, an inverter circuit 14, a high voltage generation circuit 15, a starter circuit 16, an X-ray tube device 17, and a control. The circuit 18 and the detection circuit 3 are provided.
The X-ray tube device 17 includes a stator coil 19, a rotating anode 20 (target), and an X-ray tube 21.

The AC power supply 11 is, for example, a commercial AC power supply. The diode module 12 converts an AC voltage supplied from the AC power supply 11 into a DC output. The step-up chopper circuit 13 steps up the voltage converted into direct current by the diode module 12 and supplies it to the inverter circuit 14 and the starter circuit 16.
The inverter circuit 14 converts the voltage supplied from the boost chopper circuit 13 into an AC output and outputs the AC output to the high voltage generation circuit 15. The high voltage generation circuit 15 converts the AC output supplied from the inverter circuit 14 into a high-voltage DC output and applies it to the X-ray tube device 17.

The starter circuit 16 drives, brakes or coasts the rotating anode 20 in accordance with a control signal input from the control circuit 18. The following three patterns of control signals are input from the control circuit 18.
(A) Apply AC voltage (drive)
(B) Applying DC voltage (braking)
(C) No voltage applied (inertia operation)

  That is, when the “drive” control signal is input, the starter circuit 16 applies a driving AC voltage to the rotary anode 20. When the starter circuit 16 applies an AC voltage to the stator coil 19 of the X-ray tube device 17, the rotary anode 20 rotates on the principle of an induction motor. When a “braking” control signal is input, a braking DC voltage is applied to the rotating anode 20. Thereby, the rotation speed of the rotating anode 20 can be dropped rapidly. Further, when a control signal for “inertia operation” is input, application of voltage to the rotating anode 20 is stopped.

The rotating anode 20 rotates at a high speed up to a frequency of about 180 Hz in photographing, and rotates at a rotational speed (low speed) of a frequency of about 60 Hz in fluoroscopic photographing.
In a general X-ray imaging apparatus, when a “perspective button” (not shown) is first pressed by an operator's operation, the control circuit 18 transmits a “drive (60 Hz)” control signal to the starter circuit 16. . As a result, the rotary anode 20 is driven to rotate at a rotational speed of 60 Hz. At a rotational speed of about 60 Hz, X-rays are emitted to such an extent that a fluoroscopic image can be obtained. When the “shooting button” (not shown) is pressed at a good timing (timing that the subject's body is not shaken, etc.) while watching the fluoroscopic video, the control circuit 18 “drives (180 Hz) ”Is transmitted to the starter circuit 16. As a result, the rotary anode 20 is driven at a high speed and rotates at a rotation speed of 180 Hz. At a rotation speed of about 180 Hz, intense X-rays that can be used to obtain a general image are emitted.
In the present invention, when imaging at a rotational speed of 180 Hz is completed, the control circuit 18 transmits a control signal of “inertia operation” to the starter circuit 16. As a result, the application of voltage to the rotating anode 20 is stopped. The rotating anode 20 continues to rotate with inertia, but the rotational speed gradually decreases. As a result, since a certain number of rotations is maintained, the time from the end of shooting to the start of the next shooting can be shortened, and a quick response can be made.

During such high speed (180 Hz) and low speed (60 Hz), the rotary anode 20 is present resonance frequency _{f p} which resonates.
In the present invention, the rotational speed of the rotary anode 20 drops to the vicinity of the resonance frequency f _p and braked at that timing (DC voltage application) is passed through in a short time the resonance frequency f _p vicinity. After passage of the resonance frequency f _p vicinity returns to overrun condition again. This prevents damage to the X-ray tube bearing or the like due to resonance and protects the X-ray tube device 17. In addition, since the time for braking and driving is shorter than the conventional time, power consumption can be saved.

The control circuit 18 outputs a control signal for causing the X-ray tube device 17 to (A) drive, (B) braking, or (C) inertial operation to the starter circuit 16.
In the first embodiment, when imaging (rotation speed 180 Hz) is completed, the control circuit 18 first transmits a control signal for (C) inertial operation to the starter circuit 16 and stops applying voltage to the rotary anode 20. Let It also monitors the rotational speed of the rotating anode 20 which is detected by the detection circuit 3, the rotational speed is equal to or a resonance frequency f _p vicinity, if the resonance frequency f _p vicinity, the starter circuit 16 In response to this, (B) a braking instruction is output. A braking DC voltage is applied to the rotating anode 20. If the rotational speed of the rotary anode 20 passes through the vicinity of the resonance frequency f _p, the control circuit 18 transmits a control signal (C) overrun condition, to stop the application of voltage to the rotary anode 20.

  The detection circuit 3 is configured by a sensor that detects the frequency of the rotating anode 20 such as a vibration sensor, for example, detects the number of rotations of the rotating anode 20, and outputs it to the control circuit 18.

  Next, the operation of the X-ray apparatus 1 according to the first embodiment will be described with reference to FIGS.

In the X-ray apparatus 1, the rotating anode 20 rotates at a high speed of about 180 Hz in general imaging. When photographing is finished (step S101), the control circuit 18 sends an instruction for inertial operation to the starter circuit 16 and controls to stop the application of the AC voltage (step S102). The control circuit 18 monitors the rotation number f _alpha rotating anode 20 which is output from the detection circuit 3 determines whether or not the rotation number f _alpha is smaller than the threshold value f _A (step S103). Threshold _{f A} is the number Hz of about greater than the resonance frequency _{f p.}
If the rotation speed f _α of the rotating anode 20 is equal to or greater than the threshold value f _A (step S103; Yes), the inertia operation is continued as it is.
When the rotational speed f _α of the rotary anode 20 becomes smaller than the threshold value f _A (step S103; No), the control circuit 18 instructs the starter circuit 16 to perform braking (step S104). The starter circuit 16 applies a DC voltage to the rotating anode 20.
The control circuit 18 determines whether or not the rotational speed f _α of the rotary anode 20 is equal to or greater than the threshold value f _B (step S105). Threshold _{f B} is greater than the frequency of the low speed (60 Hz), and several Hz approximately smaller than the resonance frequency _{f p.} If the rotational speed f _α of the rotary anode 20 is equal to or greater than the threshold value f _B (step S105; Yes), braking is continued. Thereafter, when the rotational speed f _α of the rotary anode 20 becomes smaller than the threshold value f _B (step S105; No), the control circuit 18 stops braking (step S106). The control circuit 18 monitors whether the rotation number f _alpha of the rotary anode 20 becomes 60 Hz (frequency of the low-speed operation) (step S107), 60 Hz inertia when not lowered rotational speed to (slow frequency of operation) Continue driving. 60Hz When the rotation number f _alpha to (slow frequency of operation) is reduced (step S107; Yes), the control circuit 18 instructs drives (intermittent drive) to maintain the rotational speed 60Hz respect starter circuit 16 (step S108 ). Thereby, a low-speed driving | running | working (60 Hz) state is maintained.

FIG. 3 is a diagram showing the transition of the rotational speed of the rotary anode 20 after the end of general imaging.
During general imaging, that is, while the control circuit 18 instructs driving, the rotational speed (frequency) of the rotary anode 20 is maintained at 180 Hz. Thereafter, when inertial operation is instructed by the control circuit 18, the rotational speed gradually decreases. When the rotational speed of the rotary anode 20 drops to about the threshold f _A of the resonance frequency f _p vicinity, the control circuit 18 instructs the braking starter circuit 16. The starter circuit 16 applies a DC voltage to brake the rotating anode 20. The number of rotations of the rotating anode 20 is rapidly reduced by braking. When the rotational speed of the rotary anode 20 is lower than the vicinity of the resonance frequency f _p (threshold f becomes smaller when than _B), the control circuit 18 instructs the overrun condition again starter circuit 16, gradually the rotational speed falls to slow 60Hz .

FIG. 4 is a diagram showing a change in the number of rotations of the rotating anode 20 when the photographing is started again after the end of the general photographing.
During general imaging, that is, while the control circuit 18 instructs driving, the frequency of the rotary anode 20 is around 180 Hz. Thereafter, when the photographing is finished, the control circuit 18 instructs inertial operation. The starter circuit 16 stops applying the voltage. As a result, the rotational speed of the rotary anode 20 gradually decreases. Thereafter, when an imaging instruction is input again, the control circuit 18 instructs the starter circuit 16 to drive, and the rotation of the rotary anode 20 is accelerated. Since acceleration is resumed from a state where the rotational speed has gradually decreased due to inertial operation, the rotational speed can be rapidly increased to a high speed (180 Hz). When photographing is finished, the control circuit 18 instructs inertial operation, and the starter circuit 16 stops applying voltage. The rotational speed of the rotating anode 20 gradually decreases.

Thus, to monitor the rotational speed of the rotating anode 20 by the detection circuit 3, it causes the overrun condition in after the shooting, to brake only when the rotational speed of the rotary anode 20 passes the resonance frequency f _p. Accordingly, the X-ray tube can be prevented from being damaged due to resonance, and the predetermined number of rotations can be quickly reached for the next imaging.

[Second Embodiment]
Next, the X-ray apparatus 1 according to the second embodiment will be described with reference to FIGS.
As shown in FIG. 5, the X-ray apparatus 2 according to the second embodiment includes an AC power supply 11, a diode module 12, a boost chopper circuit 13, an inverter circuit 14, a high voltage generation circuit 15, a starter circuit 16, and an X-ray tube. A device 17, a control circuit 18, a timer 4, and a storage unit 5 are provided. The AC power supply 11, the diode module 12, the step-up chopper circuit 13, the inverter circuit 14, the high voltage generation circuit 15, the starter circuit 16, and the X-ray tube device 17 are the same as those in the first embodiment. A reference numeral is attached, and a duplicate description is omitted.

The timer 4 is for measuring time. The actual elapsed time t after the end of shooting is measured.
The storage unit 5 has at least an estimated arrival time until the rotational speed of the rotary anode 20 reaches the vicinity of the resonance frequency fp of the X-ray tube device 17 after imaging is finished and the rotary anode 20 starts inertial operation. The estimated passage time from when the imaging is finished and the rotary anode 20 starts inertial operation until the rotational speed of the rotary anode 20 passes in the vicinity of the resonance frequency fp of the X-ray tube device 17 is stored in advance. Specifically, the following estimated times t1, t2, and t3 are stored.
t1: Time required to reach a frequency in the vicinity of the resonance frequency fp (estimated arrival time) when the inertial operation is performed after the photographing is finished,
t2: after the shooting, after the overrun condition, the time required to pass through performs braking in the vicinity of the resonance frequency fp (estimated transit time),
t3: Time required for the rotational speed to drop to 60 Hz when the inertial operation and braking while passing through the resonance frequency are performed after the photographing is finished.

When the photographing is finished, the control circuit 18 starts counting by the timer 4, and drives, brakes, and drives the starter circuit 16 according to the times t1, t2, and t3 stored in advance in the storage unit 5 with the actual elapsed time t. Send any instructions for coasting.
In addition, when a photographing instruction is input after the photographing is finished, the rotation control operation according to the times t1, t2, and t3 is finished, the driving of the rotating anode 20 is instructed, and the driving is performed at high speed (180 Hz).

The operation in the second embodiment will be described with reference to FIG. 6 and FIG.
In the X-ray apparatus 2, the rotating anode 20 is rotated at a high speed when the general imaging is finished (“starter driving” in FIG. 7). In addition, it is assumed that the control circuit 18 acquires the times t1, t2, and t3 from the storage unit 5.
When the general photographing is finished (step S201), the control circuit 18 starts measuring time by the timer 4 (step S202). In addition, a coasting operation instruction is sent to the starter circuit 16 to stop the AC output (step S203). The control circuit 18 monitors the actual elapsed time t and continues the inertia operation as it is until the time t1 is reached (step S204; No).

When the actual elapsed time t reaches time t1 (step S204; Yes), the control circuit 18 instructs the starter circuit 16 to perform braking (step S205). Time t1, as described above, the rotational speed is estimated time to reach the vicinity of the resonance frequency f _p. The starter circuit 16 applies a DC voltage to the rotating anode 20. Until the timer 4 measures the time t2 (step S206; No), the braking is continued.
Thereafter, when the actual elapsed time t reaches time t2 (step S206; Yes), the control circuit 18 stops braking (step S207). Time t2, as described above, the rotational speed is estimated time to pass through the vicinity of the resonance frequency f _p. The control circuit 18 sends a coasting operation instruction to the starter circuit 16.
Thereafter, when the timer 4 has reached the rotational speed f _α of the rotary anode 20 and the actual elapsed time t has reached the time t3 (step S208; Yes), the control circuit 18 instructs the starter circuit 16 to perform driving (intermittent driving) (step). S209). As described above, the time t3 is an estimated time until the rotational speed reaches 60 Hz (frequency of low speed operation). Thereby, a rotation speed is maintained at about 60 Hz and it will be in a low-speed driving | running state.

  If a general shooting start instruction is input midway, the control circuit 18 interrupts the timing by the timer 4 and shifts to a normal shooting operation. When the photographing is completed, the control of the starter circuit 16 according to the time measured by the timer 4 and the elapsed time is started again.

As described above, until the X-ray apparatus 2 of the second embodiment, the estimated time t1 during which the rotational speed reaches the vicinity of the resonance frequency f _p, the rotational speed passes near the resonance frequency f _p The estimated time t2 and the estimated time t3 until the rotation speed reaches 60 Hz (frequency of low speed operation) are stored in the storage unit 5 in advance, and the control circuit 18 instructs inertial operation, braking and driving according to these data. To do.
Therefore, as in the first embodiment, the rotary anode 20 together to overrun condition in after the shooting, the rotational speed of the rotary anode 20 can be braked only while passing through the resonance frequency f _p. Accordingly, the X-ray tube can be prevented from being damaged due to resonance, and the predetermined number of rotations can be quickly reached for the next imaging.

As described above, as described in the first and second embodiments, the X-ray apparatus of the present invention rotates the rotating anode 20 by causing the rotating anode 20 to coast after completion of imaging with the rotating anode 20 driven. number between the vicinity of the resonance frequency f _p of the X-ray tube is controlled so as to brake the rotating anode 20.
Thus, while maintained without lowering the possible rotational speed and the start of the next shot, by braking the rotary anode 20 in a case where the rotational speed up to the resonant frequency f _p is lowered, it is possible to pass quickly resonance frequency f _p . Therefore, the X-ray tube can be prevented from being damaged due to resonance, and the predetermined rotational speed can be quickly reached at the next imaging.

  The preferred embodiment of the X-ray apparatus 1 according to the present invention has been described above, but the present invention is not limited to the above-described embodiment. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood. For example, the control circuit (control unit) may be configured as a computer having a CPU, a volatile memory, a nonvolatile memory, and the like. In this case, a program for realizing the processing of the control circuit is stored in the nonvolatile memory, and the processing of the control circuit is realized by the CPU reading the program into the volatile memory and executing it.

DESCRIPTION OF SYMBOLS 1, 2 ... X-ray apparatus 3 ... Detection circuit 4 ... Timer 5 ... Memory | storage part 11 ... AC power supply 12 ... Diode module 13 ... Boost chopper circuit 14 ... Inverter Circuit 15 ... High voltage generation circuit 16 ... Starter circuit 17 ... X-ray tube device 18 ... Control circuit 19 ... Stator coil 20 ... Target (rotary anode)
21... X-ray tube f _p ... Resonance frequency f _α ... Anode rotation frequency f _A , f _B ... Threshold value in the vicinity of resonance frequency f _p t. · estimated time t3 · · · rpm until the estimated time t2 · · · rpm until reaching the vicinity passes near the resonance frequency f _p of the speed resonant frequency f _p is 60 Hz (the low-speed operation Frequency)

Claims (1)

An X-ray apparatus having a rotary anode type X-ray tube apparatus,
To the stator coil,
When driving the rotating anode, an alternating voltage is applied,
When braking the rotating anode, a DC voltage is applied,
A starter unit for stopping the application of voltage when the rotary anode is operated in inertia;
A control unit for controlling the starter unit;
Estimated arrival time until the rotational speed of the rotating anode reaches the vicinity of the resonance frequency of the X-ray tube device after the rotary anode starts the inertia operation after the imaging is completed, and the rotation after the imaging is completed A storage unit that stores in advance an estimated transit time from when the anode starts the inertia operation until the rotational speed of the rotary anode passes through the vicinity of the resonance frequency of the X-ray tube device;
Comprising
When the photographing is finished, the control unit causes the rotary anode to perform the inertial operation, and further counts an elapsed time since the photographing is finished and the rotary anode starts the inertial operation, and the elapsed time reaches the estimated time. The X-ray apparatus characterized in that the rotating anode is braked during a period from time to estimated passage time .

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