JP7126347B2 - X-ray equipment - Google Patents

Description

The present invention relates to an X-ray imaging apparatus that performs X-ray imaging, and more particularly to a technique for detecting failure of a tube voltage detector of a high voltage generator.

An X-ray imaging apparatus is an apparatus that creates and displays an X-ray image of a subject based on the transmitted X-ray dose obtained by irradiating the subject with X-rays. In particular, X-ray CT (Computed Tomography) equipment is a device that reconstructs and displays cross-sectional images of a subject based on the amount of transmitted X-rays acquired from various angles obtained by irradiating X-rays from the surroundings of the subject. It is widely used in diagnostic imaging.

An X-ray imaging apparatus includes an X-ray tube device that emits X-rays and a high voltage generator that generates a high voltage to be applied to the X-ray tube device. In medical X-ray equipment, the voltage applied to the X-ray tube equipment is about 120 kV. A discharge occurs inside. If electric discharge occurs in the X-ray imaging apparatus, X-ray imaging will be interrupted and image diagnosis will be hindered. In order to take appropriate countermeasures against discharge, it is necessary to identify the location where the discharge occurs.

Patent Document 1 discloses a technique for identifying in which of the X-ray tube device or the high-voltage generator the discharge is occurring, based on changes over time in the tube voltage and tube current of the X-ray tube device. .

Patent No. 5063609

However, in Patent Document 1, no consideration is given to the case where the tube voltage detection unit used to detect the tube voltage fails. The tube voltage detector is a voltage dividing circuit in which multiple resistors are connected in series. Accurate feedback control of the tube voltage as well as identification of the discharge occurrence point becomes impossible. As a result, an image obtained by X-ray imaging is adversely affected, and X-ray imaging is interrupted or re-exposed, resulting in ineffective radiation exposure to the subject.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an X-ray imaging apparatus capable of detecting a failure of a tube voltage detection section of a high voltage generator.

In order to achieve the above object, the present invention provides a method for determining whether the pulse width of the control signal of an inverter provided in an X-ray imaging apparatus, the effective value of the output current, or the input power to the converter is within a predetermined normal range. It is characterized by detecting a failure of the tube voltage detection unit based on.

More specifically, a converter that converts an AC voltage to a DC voltage, an inverter that converts the DC voltage to a high frequency voltage, a high voltage transformer that boosts the high frequency voltage to a high frequency high voltage, and a high frequency high voltage A high-voltage rectifier that rectifies and generates a DC high voltage, an X-ray tube device that emits X-rays when the DC high voltage is applied, and a tube voltage that detects the tube voltage applied to the X-ray tube device. An X-ray imaging apparatus comprising a detection unit and an inverter control unit that controls the inverter based on the detection result of the tube voltage detection unit, wherein the pulse width of the control signal of the inverter or the effective value of the output current or It is characterized by comprising a failure detection unit that determines that the tube voltage detection unit is out of order when the input power to the converter is out of a predetermined normal range.

According to the present invention, it is possible to provide an X-ray imaging apparatus capable of detecting failure of a tube voltage detection section of a high voltage generator.

1 is a diagram showing the overall configuration of an X-ray CT apparatus 1 as an example of an X-ray imaging apparatus; FIG. 2 is a diagram showing the configuration of a high voltage generator 111. FIG. 4 is a diagram showing an example of a tube voltage detection unit 205; FIG. 1 is a diagram showing the configuration of an X-ray control device 110 according to a first embodiment; FIG. 4 is a table showing the correspondence between X-ray irradiation conditions and normal ranges of pulse widths. FIG. 10 is a diagram showing pulse widths when the tube voltage detection unit 205 is normal and when it fails. It is a figure which shows the flow of a process of 1st embodiment. FIG. 4 is a diagram showing the configuration of a high voltage generator 111 of a second embodiment; FIG. 2 is a diagram showing the configuration of an X-ray control device 110 of a second embodiment; FIG. 4 is a table showing correspondence between X-ray irradiation conditions and normal ranges of output current effective values. FIG. 4 is a diagram showing the configuration of a high voltage generator 111 of a third embodiment; FIG. 10 is a diagram showing the configuration of an X-ray control device 110 of a third embodiment; 4 is a table showing the correspondence between X-ray irradiation conditions and normal ranges of input power; FIG. 10 is a diagram showing the configuration of an X-ray control device 110 of a fourth embodiment;

[First embodiment]
Preferred embodiments of the X-ray imaging apparatus according to the present invention will be described below with reference to the accompanying drawings. In the following description and accompanying drawings, constituent elements having the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

FIG. 1 is a block diagram showing the overall configuration of an X-ray CT apparatus, which is an example of an X-ray imaging apparatus. Note that the X-ray imaging apparatus is not limited to the X-ray CT apparatus, and may be an X-ray fluoroscopic apparatus or the like. As shown in FIG. 1, the X-ray CT apparatus 1 includes a scan gantry section 100 and an operation unit 120. As shown in FIG.
The scan gantry unit 100 includes an X-ray tube device 101, a rotating disk 102, a collimator 103, an X-ray detector 106, a data collection device 107, a bed device 105, a gantry control device 108, and a bed control device 109. , an X-ray controller 110 and a high voltage generator 111 . The X-ray tube device 101 is a device that irradiates the subject 10 placed on the couch device 105 with X-rays. A collimator 103 is a device that limits the irradiation range of X-rays. The rotating disk 102 has an opening 104 into which the subject 10 placed on the bed device 105 is inserted, and is equipped with the X-ray tube device 101 and the X-ray detector 106. Rotate the device 106 around the subject 10 .

The X-ray detector 106 is arranged to face the X-ray tube device 101 and measures the spatial distribution of transmitted X-rays by detecting the X-rays transmitted through the subject 10 . The detection elements of the X-ray detector 106 may be arranged one-dimensionally in the rotational direction of the rotating disk 102, or two-dimensionally arranged in the rotational direction of the rotating disk 102 and the rotation axis direction. The data collection device 107 is a device that collects the X-ray dose detected by the X-ray detector 106 as digital data. A gantry controller 108 is a device that controls the rotation and tilt of the rotating disk 102 .

The bed control device 109 is a device that controls the up-down, front-back, left-right movement of the bed device 105 . A high voltage generator 111 is a device that generates a high voltage to be applied to the X-ray tube device 101 . The X-ray control device 110 is a device that controls the output of the high voltage generator 111 and detects a failure of a tube voltage detection section, which will be described later. The high voltage generator 111 and the X-ray controller 110 will be described later in detail.

The operation unit 120 includes an input device 121, an image processing device 122, a display device 125, a storage device 123, and a system control device . The input device 121 is a device for inputting the name of the subject 10, examination date and time, imaging conditions, etc. Specifically, it is a keyboard, pointing device, touch panel, or the like. The image processing device 122 is a device that performs arithmetic processing on the measurement data sent from the data acquisition device 107 to reconstruct a CT image. The display device 125 is a device that displays CT images and the like created by the image processing device 122, and is specifically a liquid crystal display or the like. The storage device 123 is a device for storing the data collected by the data collection device 107, the image data of the CT image created by the image processing device 122, and the like, and is specifically an HDD (Hard Disk Drive) or the like. The system controller 124 is a device that controls these devices, the gantry controller 108 , the bed controller 109 and the X-ray controller 110 .

Based on the imaging conditions input from the input device 121, the high voltage generator 111 generates the tube voltage and the tube current applied to the X-ray tube device 101, so that the X-rays corresponding to the imaging conditions are generated by the X-ray tube device. A subject 10 is irradiated from 101 . The X-ray detector 106 detects the X-rays emitted from the X-ray tube device 101 and transmitted through the subject 10 with a large number of X-ray detection elements, and measures the distribution of the transmitted X-rays. The rotating disk 102 is controlled by the gantry control device 108 and rotates based on the imaging conditions input from the input device 121, particularly the rotation speed and the like. The bed device 105 is controlled by the bed control device 109 and operates based on the imaging conditions, particularly the spiral pitch, etc., input from the input device 121 .

X-ray irradiation from the X-ray tube device 101 and X-ray measurement by the X-ray detector 106 are repeated as the rotating disk 102 rotates, thereby acquiring projection data from various angles. The projection data are associated with a view representing each angle, a channel (ch) number which is a detection element number of the X-ray detector 106, and a row number. The acquired projection data from various angles are transmitted to the image processing device 122 . The image processing device 122 reconstructs a CT image by performing back projection processing on the transmitted projection data from various angles. A CT image obtained by reconstruction is displayed on the display device 125 .

The X-ray CT apparatus 1 may be connected to an in-hospital server or an extra-hospital server via a network (not shown), and may read necessary data from each server as needed.

The high voltage generator 111 will be described with reference to FIG. High voltage generator 111 includes converter 201 , inverter 202 , high voltage transformer 203 , high voltage rectifier 204 and tube voltage detector 205 .

The converter 201 is a device that is connected to a commercial AC power supply 200 and converts the AC voltage of the AC power supply 200 into a DC voltage.

Inverter 202 is a device that is connected to converter 201 and converts the DC voltage output from converter 201 into a high-frequency voltage that is an AC voltage with a higher frequency than the AC voltage of AC power supply 200 . The inverter 202 has a plurality of switches, and by periodically switching ON/OFF of these switches at a predetermined timing, the DC voltage is repeatedly output in the forward direction and in the reverse direction. converts the DC voltage into a high frequency voltage. The converter 201 and the inverter 202 are controlled by the X-ray control device 110 according to the imaging conditions input from the input device 121, particularly tube voltage, tube current, and the like.

The high voltage transformer 203 is connected to the inverter 202, boosts the high frequency voltage output from the inverter 202, and outputs a high frequency high voltage. The step-up ratio is determined by the turns ratio between the primary and secondary windings of high voltage transformer 203 . The high voltage rectifier 204 is connected to the high voltage transformer 203 and rectifies the high frequency high voltage boosted by the high voltage transformer 203 . High voltage rectifier 204 may include a smoothing capacitor that smoothes pulsations in the rectified voltage waveform.

A tube voltage detection unit 205 is a circuit that detects a tube voltage, which is a voltage applied to the X-ray tube device 101, and is connected in parallel with the X-ray tube device 101. FIG. The detected tube voltage value is input to the X-ray controller 110 . The X-ray control device 110 compares the detected tube voltage value with the tube voltage value set by the operation unit 120, and controls the pulse width, which is the period during which the switch of the inverter 202 is turned on, based on the comparison result. do. Control of the pulse width will be described later.

FIG. 3 shows an example of the tube voltage detector 205. As shown in FIG. FIG. 3(a) shows an example of a circuit when the X-ray tube device 101 is of a one-sided ground type, where In1 and In2 are input terminals, Out is an output terminal, R1 is a voltage dividing resistor, and R2 is a detection resistor. The voltage dividing resistor R1 and the detection resistor R2 are resistors forming a voltage dividing circuit and are connected in series. An output terminal Out is provided at the connection point of both resistors, and input terminals In1 and In2 are provided on the opposite side of the connection point, and the input terminal In2 is at ground potential. The input terminals In1 and In2 are connected to the high voltage rectifier 204 and the X-ray tube device 101, and the output terminal Out is connected to the X-ray controller 110. FIG. The voltage dividing resistor R1 has a sufficiently large resistance value compared to the detection resistor R2, for example, R1=100MΩ for R2=1Ω. With such a circuit configuration, the tube voltage Vt, which is the voltage applied to the X-ray tube device 101, is divided by the voltage dividing resistor R1 and the detection resistor R2, and the voltage applied to the detection resistor R2 is Vt/(1 +10 ⁸ ). In other words, even if the tube voltage Vt is a high voltage of 80kV to 140kV, only a low voltage of about 0.8mV to 1.4mV is applied to the detection resistor R2, and by measuring the voltage at the output terminal Out The value of the tube voltage Vt can be easily known.

Fig. 3(b) shows an example of a circuit when the X-ray tube device 101 is of the neutral point grounding type. In1 and In2 are input terminals, Out1 and Out2 are output terminals, R11 and R21 are voltage dividing resistors, R12 and R22 is the sense resistor. The voltage dividing resistor R11 and the detection resistor R12, as well as the voltage dividing resistor R21 and the detection resistor R22, constitute a voltage dividing circuit and are connected in series. Output terminal Out1 is provided at the connection point of voltage dividing resistor R11 and detection resistor R12, output terminal Out2 is provided at the connection point of voltage dividing resistor R21 and detection resistor R22, and the connection point of detection resistor R12 and detection resistor R22 is grounded. is the electric potential. The voltage dividing resistor R11 is provided with an input terminal In1, and the voltage dividing resistor R21 is provided with an input terminal In2. The input terminals In1 and In2 are connected to the high voltage rectifier 204 and the X-ray tube device 101, and the output terminals Out1 and Out2 are connected to the X-ray controller 110. FIG. The voltage dividing resistors R11 and R21 have sufficiently large resistance values compared to the detection resistors R12 and R22, for example, R11=R21=100MΩ for R12=R22=1Ω. With such a circuit configuration, the tube voltage Vt, which is the voltage applied to the X-ray tube device 101, is divided between the input terminal In1 side and the input terminal In2 side with the ground potential as a boundary. If it is Vt/2, the voltage at the input terminal In2 is -Vt/2. The voltage Vt/2 on the input terminal In1 side is divided by the voltage dividing resistor R11 and the detection resistor R12, the voltage -Vt/2 on the input terminal In2 side is divided by the voltage dividing resistor R21 and the detection resistor R22, and the detection resistor R12 , and R22 are (Vt/2)/(1+10 ⁸ ) and −(Vt/2)/(1+10 ⁸ ), respectively. In other words, even if the tube voltage Vt is high, only a low voltage is applied to the detection resistors R12 and R22. can be known to

The X-ray control device 110 will be described with reference to FIG. The X-ray control device 110 may be configured with dedicated hardware, or may be configured with software that operates on an arithmetic processing unit. In the following description, the case of being configured by software will be described. The X-ray control device 110 has an inverter control section 400 and a failure detection section 410 .

The inverter control section 400 generates a signal for controlling the inverter 202 and has a target tube voltage acquisition section 401 and a pulse width adjustment section 402 . The target tube voltage acquisition unit 401 acquires the tube voltage value set by the operation unit 120 as the target tube voltage, and transmits the target tube voltage to the pulse width adjustment unit 402 .

The pulse width adjustment unit 402 compares the detected tube voltage, which is the tube voltage detected by the tube voltage detection unit 205, with the target tube voltage, and adjusts the pulse width, which is the period during which the switch of the inverter 202 is turned on according to the comparison result. to adjust. That is, if the detected tube voltage is lower than the target tube voltage, the pulse width is widened, and if the detected tube voltage is higher than the target tube voltage, the pulse width is narrowed. The switch of the inverter 202 operates according to the pulse width adjusted by the pulse width adjustment unit 402, and the pulse width adjustment is repeated, so that the detected tube voltage matches the target tube voltage. At this time, the pulse width also falls within a predetermined range, which varies depending on the target tube voltage.

The failure detection unit 410 determines whether or not the tube voltage detection unit 205 has failed, and has a normal range acquisition unit 411 and a pulse width comparison unit 412 . A normal range acquisition unit 411 acquires the normal range of the pulse width.

The normal range of pulse width is determined in advance according to the X-ray irradiation conditions, and is stored in the storage device 123 as a table as shown in FIG. 5, for example. In the table of FIG. 5, the normal range of pulse width is defined for each X-ray irradiation condition. For example, the normal range of pulse width WL2 to WU2 corresponds to X-ray irradiation condition X2. That is, when the X-ray irradiation conditions such as the target tube voltage are set, the normal range acquisition unit 411 reads the normal range of pulse width from the table in FIG. The normal range of the pulse width for each X-ray irradiation condition corresponds to the allowable range of the tube voltage based on the normal pulse width under each X-ray irradiation condition obtained when the tube voltage detection unit 205 is in a normal state. is set.

The pulse width comparison unit 412 determines whether the pulse width adjusted by the pulse width adjustment unit 402 is within the normal range. If the adjusted pulse width is outside the normal range, the tube voltage detection unit 205 determine that it is defective.

A change in the pulse width of the inverter control signal when the tube voltage detection unit 205 fails will be described with reference to FIG. FIG. 6 shows tube voltage waveforms and pulse widths when the tube voltage detector 205 is normal or faulty. FIG. 6(a) shows the tube voltage waveform, where the solid line indicates the case where the tube voltage detection unit 205 is normal, and the dotted line indicates the case where it fails. FIGS. 6(b) to 6(d) are inverter control signals.

When the tube voltage detection unit 205 is normal, that is, when the resistance values of the voltage dividing resistor (R1 in FIG. 4(a)) and the detection resistor (R2 in FIG. 4(a)) remain at their initial values, the tube voltage is The target tube voltage is controlled. The control signal for the inverter at this time is as shown in FIG. 6(c), and the pulse width is W0.

When the tube voltage detection unit 205 fails and the resistance value of the voltage dividing resistor becomes larger than the initial value or the resistance value of the detection resistor becomes smaller than the initial value, the detected tube voltage becomes lower than the actual tube voltage. Therefore, the tube voltage is controlled to be higher than the target tube voltage. The control signal for the inverter at this time is as shown in FIG. 6(b), and the pulse width is W1, which is wider than the normal pulse width W0.

When the tube voltage detection unit 205 fails and the resistance value of the voltage dividing resistor becomes smaller than the initial value, or the resistance value of the detection resistor becomes larger than the initial value, the detected tube voltage becomes higher than the actual tube voltage. also increases, the tube voltage is controlled to be smaller than the target tube voltage. The control signal for the inverter at this time is as shown in FIG. 6(d), and the pulse width is W2, which is narrower than the normal pulse width W0.

In other words, if the pulse width of the inverter control signal is too wide or too narrow, it can be determined that the tube voltage detector 205 is out of order. The pulse width is compared with the normal range, and failure of the tube voltage detector 205 is determined based on the comparison result. Also, if X-ray imaging is performed without controlling the tube voltage to the target tube voltage, the acquired image will be different from the image desired by the operator, and the subject may be ineffectively exposed to radiation. Therefore, when the pulse width comparison unit 412 determines that the tube voltage detection unit 205 is out of order, it instructs the pulse width adjustment unit 402 to set the pulse width to zero, that is, to interrupt the X-ray imaging. can be

The flow of processing executed by the X-ray control apparatus 110 having the above components will be described with reference to FIG.

(S701)
The X-ray controller 110 receives the X-ray irradiation conditions set by the operation unit 120 . The X-ray irradiation conditions are sent to the target tube voltage acquisition unit 401 of the inverter control unit 400 and the normal range acquisition unit 411 of the failure detection unit 410 .

(S702)
A normal range acquisition unit 411 acquires the normal range of the pulse width. Specifically, the X-ray irradiation conditions acquired in S701 are compared with the table shown in FIG. 5 to read out the normal range of the pulse width according to the X-ray irradiation conditions.

(S703)
The X-ray controller 110 initiates X-ray irradiation. Specifically, the inverter control unit 400 operates the inverter 202 according to the X-ray irradiation conditions.

(S704)
A pulse width comparator 412 measures the pulse width. Specifically, the pulse width comparator 412 receives the pulse width adjusted by the pulse width adjuster 402 .

(S705)
A pulse width comparator 412 determines whether the pulse width is within the normal range. Specifically, the normal range acquired in S702 and the pulse width measured in S704 are compared. If it is within the normal range, the process proceeds to S706, and if not within the normal range, the process proceeds to S707.

(S706)
Inverter control unit 400 determines whether or not a predetermined X-ray irradiation time has elapsed. The X-ray irradiation time is included in the X-ray irradiation conditions received in S701. If the predetermined X-ray irradiation time has passed, the process ends, otherwise the process returns to S704.

(S707)
The pulse width comparator 412 determines that the tube voltage detector 205 is out of order. The pulse width comparison unit 412 may issue an instruction to the pulse width adjustment unit 402 to immediately interrupt X-ray imaging, or display failure detection on the display device 125 to present it to the operator. When the pulse width adjustment unit 402 receives an X-ray imaging interruption instruction, the inverter control unit 400 included in the X-ray control device 110 stops the operation of the inverter 202 . The X-ray control device 110 may stop the operation of the converter 201 to interrupt X-ray imaging.

With the flow of processing described above, it is possible to detect a failure of the tube voltage detection unit 205 of the high voltage generator 111 . In addition, by interrupting X-ray imaging when a failure is detected, it is possible to prevent ineffective radiation exposure to the subject. Further, by displaying the failure detection and presenting it to the operator, it is possible to quickly respond to the failure.

Also, the flow of processing shown in FIG. 7 may be executed for each X-ray imaging, or may be executed at a predetermined timing. For example, X-ray irradiation may be repeated under predetermined conditions at the beginning of the day to warm up the X-ray tube device 101, so the flow of processing in FIG. 7 may be executed at that timing. At this time, the table shown in FIG. 5 may be prepared only for the X-ray irradiation conditions used for warm-up operation. By narrowing down the X-ray irradiation conditions to be tabulated, the storage capacity of the storage device 123 can be saved.

[Second embodiment]
In the first embodiment, detection of failure of the tube voltage detector 205 based on whether the pulse width of the control signal for the inverter is within the normal range has been described. Failure of the tube voltage detector 205 can also be detected by monitoring parameters other than the pulse width, such as the output current of the inverter. Therefore, in the present embodiment, failure detection based on monitoring of the output current of the inverter will be described.

A high voltage generator 111 of the present embodiment will be described with reference to FIG. The difference between the present embodiment and the first embodiment is that an output current detection unit 801 is added, and other configurations are the same as those of the first embodiment, so description thereof will be omitted. The output current detection unit 801 is a device for detecting the output current of the inverter 202, and is specifically a current transformer or the like. The output current detection unit 801 is connected to the X-ray control device 110 and outputs the output current of the inverter 202 .

The X-ray control device 110 of this embodiment will be described with reference to FIG. The difference between the present embodiment and the first embodiment is the failure detection unit 910, and the rest of the configuration is the same as that of the first embodiment, so the description is omitted. A failure detection unit 910 determines whether or not the tube voltage detection unit 205 has failed, and has a normal range acquisition unit 911 and an output current comparison unit 912 .

A normal range acquisition unit 911 acquires the normal range of the output current effective value of the inverter 202 . The normal range of the output current effective value is determined in advance according to the X-ray irradiation conditions, and stored in the storage device 123 as a table as shown in FIG. 10, for example. In the table of FIG. 10, the normal range of the output current effective value is defined for each X-ray irradiation condition. For example, the normal range IL2 to IU2 of the output current effective value corresponds to the X-ray irradiation condition X2. That is, when the X-ray irradiation conditions such as the target tube voltage are set, the normal range acquisition unit 911 reads the normal range of the output current effective value from the table of FIG.

Output current comparator 912 converts the output current detected by output current detector 801 into an effective value, and then determines whether the output current effective value is within the normal range. If it is outside of , it is determined that the tube voltage detection unit 205 is out of order.

With the configuration described above, it is possible to detect failure of the tube voltage detection section 205 of the high voltage generator 111 based on the monitoring of the output current of the inverter 202 . Further, an instruction to interrupt X-ray imaging accompanying failure detection and presentation of failure detection to the operator are the same as in the first embodiment.

[Third Embodiment]
In the first embodiment and the second embodiment, detection of failure of the tube voltage detector 205 based on whether the pulse width of the inverter control signal or the effective value of the output current is within the normal range has been described. Failure of the tube voltage detector 205 can also be detected by monitoring parameters other than the inverter, such as the input power to the converter. Therefore, in the present embodiment, failure detection based on monitoring of input power to the converter will be described.

A high voltage generator 111 of this embodiment will be described with reference to FIG. The difference between this embodiment and the first embodiment is that an input power detection unit 1101 is added, and other configurations are the same as those of the first embodiment, so description thereof will be omitted. Input power detection unit 1101 is a device that detects the input power to converter 201, and is specifically a device such as a combination of a current transformer and a voltmeter. Input power detector 1101 is connected to X-ray control device 110 and outputs input power to converter 201 .

The X-ray control device 110 of this embodiment will be described with reference to FIG. The difference between the present embodiment and the first embodiment is the failure detection unit 1210, and other configurations are the same as those of the first embodiment, so the description is omitted. A failure detection unit 1210 determines whether or not the tube voltage detection unit 205 has failed, and has a normal range acquisition unit 1211 and an input power comparison unit 1212 .

Normal range acquisition section 1211 acquires the normal range of the input power to converter 201 . The normal range of input power is determined in advance according to the X-ray irradiation conditions, and is stored in the storage device 123 as a table as shown in FIG. 13, for example. The table in FIG. 13 defines the normal range of input power for each X-ray irradiation condition. For example, the normal range of input power PL2 to PU2 corresponds to X-ray irradiation condition X2. That is, when the X-ray irradiation conditions such as the target tube voltage are set, the normal range acquisition unit 1211 reads out the normal range of input power from the table in FIG.

The input power comparator 1212 determines whether the input power detected by the input power detector 1101 is within the normal range. If the input power is outside the normal range, the tube voltage detector 205 is out of order. judge that there is

With the configuration described above, it is possible to detect failure of tube voltage detection section 205 of high voltage generator 111 based on monitoring of input power to converter 201 . Further, an instruction to interrupt X-ray imaging accompanying failure detection and presentation of failure detection to the operator are the same as in the first embodiment.

[Fourth embodiment]
In the first embodiment, detection of failure of the tube voltage detector 205 based on whether the pulse width of the control signal for the inverter is within the normal range has been described. By the way, it takes a finite amount of time, for example several milliseconds, for the tube voltage to reach a steady state after the inverter 202 starts operating. It changes according to the difference between That is, the pulse width is not constant until the tube voltage reaches a steady state, which is not preferable for determining whether the pulse width is within the normal range. Also, it is not preferable to determine whether the pulse width is within the normal range during discharge in the X-ray tube device 101 or the high voltage generator 111 or immediately after the discharge. Therefore, in the present embodiment, determination of failure detection at appropriate timing will be described.

The X-ray control device 110 of this embodiment will be described with reference to FIG. The difference between this embodiment and the first embodiment is that a determination trigger generation unit 1401 is added, and other configurations are the same as those of the first embodiment, so description thereof will be omitted.

The determination trigger generation unit 1401 generates a trigger at a timing suitable for failure detection determination, and transmits the trigger to the pulse width comparison unit 412 . The trigger is generated after the tube voltage reaches a steady state, or after discharge occurs in the X-ray tube device 101 or the high voltage generator 111, and the X-ray tube device 101 or the high voltage generator 111 After returning to normal operation.

Determination of whether or not the tube voltage has reached a steady state is made, for example, by determining whether or not a predetermined time has elapsed since the start of X-ray irradiation. The predetermined time is set to the time required for the tube voltage to reach a steady state. Since the time required for the tube voltage to reach a steady state differs for each X-ray irradiation condition, a predetermined time may be set for each X-ray irradiation condition, or the steady state may be reached under all X-ray irradiation conditions. The longest time may be set.

Further, whether or not the tube voltage has reached a steady state may be determined based on whether or not the time rate of change of the tube voltage has become equal to or less than a predetermined value. That is, the tube voltage may be monitored at a predetermined sampling period, and it may be determined that the tube voltage has reached a steady state when the deviation of the tube voltage between samplings is equal to or less than a predetermined threshold value.

Whether or not the X-ray tube device 101 and the high voltage generator 111 have recovered from discharge to normal operation is determined, for example, by determining whether or not a predetermined time has passed since the discharge was detected. An arcing recovery period, which is a period during which inverter 202 is stopped immediately after discharging, is set as a predetermined time. The arcing recovery period is about several tens of milliseconds.

After receiving the trigger from the determination trigger generation unit 1401, the pulse width comparison unit 412 starts determining whether the pulse width is within the normal range.

By adopting such a configuration, the pulse width comparison unit 412 can perform judgment is started. As a result, it is possible to improve the accuracy of determining whether the pulse width is within the normal range. Further, an instruction to interrupt X-ray imaging accompanying failure detection and presentation of failure detection to the operator are the same as in the first embodiment.

It should be noted that the X-ray imaging apparatus of the present invention is not limited to the above-described embodiments, and can be embodied by modifying the constituent elements without departing from the gist of the invention. Also, a plurality of constituent elements disclosed in the above embodiments may be appropriately combined. Furthermore, some components may be deleted from all the components shown in the above embodiments. For example, the determination trigger generator 1401 of the fourth embodiment may be added to the second embodiment or the third embodiment.

1 X-ray CT device, 10 test object, 100 scanning gantry, 101 X-ray tube device, 102 rotating disk, 103 collimator, 104 opening, 105 bed device, 106 X-ray detector, 107 data acquisition device, 108 gantry control Equipment, 109 Bed control device, 110 X-ray control device, 111 High voltage generator, 120 Operation unit, 121 Input device, 122 Image processing device, 123 Storage device, 124 System control device, 125 Display device, 201 Converter, 202 Inverter , 203 high voltage transformer, 204 high voltage rectifier, 205 tube voltage detector, 400 inverter controller, 401 target tube voltage acquisition unit, 402 pulse width adjustment unit, 410 failure detection unit, 411 normal range acquisition unit, 412 pulse width Comparison unit 801 Output current detection unit 910 Failure detection unit 911 Normal range acquisition unit 912 Output current comparison unit 1101 Input power detection unit 1210 Failure detection unit 1211 Normal range acquisition unit 1212 Input power comparison unit 1401 Judgment trigger generator

Claims (7)

A converter that converts an AC voltage to a DC voltage, an inverter that converts the DC voltage to a high frequency voltage, a high voltage transformer that boosts the high frequency voltage to a high frequency high voltage, and a high frequency high voltage that is rectified to produce a high DC voltage. an X-ray tube device that emits X-rays by applying the DC high voltage; a tube voltage detection unit that detects the tube voltage applied to the X-ray tube device; An X-ray imaging apparatus comprising an inverter control unit that controls the inverter based on the detection result of the voltage detection unit,
A failure detection unit that determines that the tube voltage detection unit is out of order when the pulse width of the control signal for the inverter is outside a predetermined normal range,
The failure detection unit reads out the normal range of the pulse width based on the set X-ray irradiation conditions from a table in which the normal range of the pulse width of the control signal of the inverter is determined for each X-ray irradiation condition. An X-ray imaging apparatus characterized by comparing a normal range with a measured pulse width. A converter that converts an AC voltage to a DC voltage, an inverter that converts the DC voltage to a high frequency voltage, a high voltage transformer that boosts the high frequency voltage to a high frequency high voltage, and a high frequency high voltage that is rectified to produce a high DC voltage. an X-ray tube device that emits X-rays by applying the DC high voltage; a tube voltage detection unit that detects the tube voltage applied to the X-ray tube device; An X-ray imaging apparatus comprising an inverter control unit that controls the inverter based on the detection result of the voltage detection unit,
A failure detection unit that determines that the tube voltage detection unit is out of order when the input power to the converter is outside a predetermined normal range,
The failure detection unit reads the normal range of input power to the converter based on the set X-ray irradiation conditions from a table in which the normal range of input power to the converter is determined for each X-ray irradiation condition, and reads out the normal range of the input power. with the measured input power. 3. The X-ray imaging apparatus according to claim 1, wherein the X-ray irradiation conditions stored in said table are X-ray irradiation conditions used for warming up said X-ray tube device. Line photography device. A converter that converts an AC voltage to a DC voltage, an inverter that converts the DC voltage to a high frequency voltage, a high voltage transformer that boosts the high frequency voltage to a high frequency high voltage, and a high frequency high voltage that is rectified to produce a high DC voltage. an X-ray tube device that emits X-rays by applying the DC high voltage; a tube voltage detection unit that detects the tube voltage applied to the X-ray tube device; An X-ray imaging apparatus comprising an inverter control unit that controls the inverter based on the detection result of the voltage detection unit,
Failure to determine that the tube voltage detection unit is out of order when the pulse width of the control signal of the inverter, the effective value of the output current, or the input power to the converter is outside a predetermined normal range. Equipped with a detection unit,
An X-ray imaging apparatus, further comprising a determination trigger generation unit that generates a trigger for starting the operation of the failure detection unit. The X-ray imaging apparatus according to claim 4,
The X-ray imaging apparatus, wherein the determination trigger generation unit generates the trigger after a predetermined time has elapsed since X-ray irradiation was started. The X-ray imaging apparatus according to claim 4,
The X-ray imaging apparatus, wherein the determination trigger generation unit generates the trigger after a time rate of change of the tube voltage detected by the tube voltage detection unit becomes equal to or less than a predetermined value. The X-ray imaging apparatus according to claim 4,
The X-ray imaging apparatus, wherein the determination trigger generation unit generates the trigger after a predetermined time has elapsed since discharge occurred in the X-ray imaging apparatus.

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