X-ray fluoroscope and control method of the same

Abstract

To provide an X-ray fluoroscope which is hardly affected by a change of the surrounding environment and capable of displaying a display image of desired luminance from the start of fluoroscopy.SOLUTION: The filament of an X-ray tube is supplied with a current for heating the filament. A tube voltage pulse is applied between the filament and an anode at a set pulse rate. A tube current detector measures a tube current flowing between the filament and the anode after application of one tube voltage pulse begins. A pulse width control unit determines a timing, on the basis of the tube current value measured by the tube current detector, at which a tube current-time product while the tube voltage pulse is being applied reaches a predetermined value. Application of the tube voltage is shut off at the determined timing. In this way, the pulse width of the tube voltage pulse is adjusted for each pulse.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an X-ray fluoroscopy apparatus.

Background Art

[0002] As one of the methods for performing fluoroscopic imaging using an X-ray fluoroscopy apparatus, pulse fluoroscopy is known. In pulse fluoroscopy, pulsed X-rays are irradiated onto a subject, the X-rays transmitted through the subject are detected by an X-ray detector, and an image is generated and displayed on a display device in real time. By repeating this process at a frequency of 4 to 30 fps (frames per second), a moving X-ray image is displayed. The pulsed X-rays are irradiated with a preset tube voltage, tube current, and pulse width. When adjusting the brightness of the image, the tube voltage condition, tube current condition, or pulse width condition (pulse width of about 5 to 20 ms) is changed automatically or manually.

[0003] Patent Document 1 discloses a technique in which fluoroscopy is started and the pulse width of the tube voltage is set to a predetermined pulse width wider than that in the steady fluoroscopic state for a predetermined period until the temperature of the filament reaches the temperature in the steady fluoroscopic state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the tube voltage of the X-ray fluoroscopy apparatus, real-time feedback processing can be performed at high speed, and a necessary constant tube voltage can be output from the start of fluoroscopy. On the other hand, the tube current depends on the temperature of the filament of the X-ray tube, and in order to keep the tube current constant, it is necessary to perform feedback control of the filament current that heats the filament.

[0006] However, the response speed of the filament temperature is as slow as 10 ms or more. Also, at the start of fluoroscopy, the filament temperature gradually rises. Therefore, it is not possible to perform high-speed feedback control of the tube current of the pulsed X-ray. This causes image defects at the start of fluoroscopy and the hunting phenomenon where the luminance fluctuates even when automatic luminance adjustment is performed.

[0007] The technique of Patent Document 1 sets the pulse width of the tube voltage to a certain wide pulse width for a certain period of time at the start of fluoroscopy. Therefore, it is necessary to determine that time and pulse width in advance. Since the time required for the rise of the filament temperature at the start of fluoroscopy and the rise curve vary depending on the environment such as the ambient temperature, the technique of Patent Document 1 cannot cope with changes in the ambient environment.

[0008] An object of the present invention is to provide an X-ray fluoroscopy apparatus that is less affected by changes in the ambient environment and can display a display image with a desired luminance from the start of fluoroscopy.

Means for Solving the Problems

[0009] To achieve the above object, the X-ray fluoroscopy apparatus of the present invention includes an X-ray tube including a filament as a cathode and an anode, a filament heater that supplies a current for heating the filament, a tube voltage control unit that applies a tube voltage pulse between the filament and the anode at a set pulse rate, a tube current detector, and a pulse width control unit. The tube current detector measures the tube current flowing between the filament and the anode after the start of application of one tube voltage pulse. The pulse width control unit obtains the cutoff timing of the tube voltage pulse for causing the tube current time integral during which the tube voltage pulse is applied to reach a predetermined value based on the value of the tube current measured by the tube current detector, and adjusts the pulse width of the tube voltage pulse for each pulse by instructing the tube voltage control unit to cut off the application of the tube voltage at the obtained cutoff timing.

Effects of the Invention

[0010] According to the present invention, for each X-ray pulse to be irradiated, the tube current is measured and the pulse width is adjusted, so that the X-ray fluoroscopic image with a desired luminance can be displayed from the start of fluoroscopy without being affected by ambient environmental changes.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0012] Hereinafter, the X-ray fluoroscopic apparatus according to the embodiments of the present invention will be described with reference to the drawings.

[0013] The fluoroscopic X-ray apparatus according to the present embodiment detects the tube current immediately after the start of irradiation for each X-ray pulse irradiated, determines the cut-off time (pulse width) of the tube voltage pulse that causes the tube current time integral to reach a predetermined value, and cuts off the tube voltage when the cut-off time is reached. As a result, even during the period from when the filament temperature is low immediately after the start of fluoroscopy until it reaches the target temperature, the tube current time integral for each irradiated X-ray pulse can be kept constant.

[0014] When the tube voltage is constant, the tube current time integral substantially corresponds to the time integral of the X-ray dose irradiated from the X-ray tube. In pulsed fluoroscopy, the X-rays that reach the X-ray detector in one pulse of X-rays are integrated and detected, and are used for generating an image of one frame. Therefore, if the tube current time integral for each pulse is constant, the image brightness can be kept constant, and the brightness of the X-ray image can be stabilized.

[0015] This will be specifically described below.

[0016] <<Embodiment 1>> The fluoroscopic X-ray apparatus according to Embodiment 1 will be described with reference to FIGS. 1 to 3.

[0017] FIG. 1 is a block diagram showing the configuration of the fluoroscopic X-ray apparatus according to Embodiment 1. FIGS. 2(a) to (f) respectively show the target average tube current, filament current, filament temperature, tube current, tube voltage, and the switching timing between the integration time and the readout time of the X-ray detector. FIG. 3 is a flow for explaining the operation of the fluoroscopic X-ray apparatus.

[0018] As shown in FIG. 1, the fluoroscopic X-ray apparatus includes an X-ray tube 103, an X-ray detector 104, a filament heater 107, a tube voltage control unit 102, a tube current detector 106, a pulse width control unit 109, a control unit 112, an image processing unit 115, a monitor 116, and an input unit 117.

[0019] The X-ray tube 103 has a structure in which a filament 114 as the cathode and an anode 113 are enclosed in a container 103a. The container 103a is made of a material that transmits X-rays in the region through which the X-rays emitted from the anode 113 pass. Although not shown, a drive unit for rotating the anode 113 is connected to the anode 113.

[0020] Filament heaters 107 are connected to both ends of the filament 14, and the filament heaters 107 supply current to and heat the filament 114. Thermoelectrons are emitted from the heated filament 114.

[0021] The tube voltage control unit 102 applies a tube voltage pulse between the filament 114 and the anode 113 at a set pulse rate. As a result, the thermoelectrons emitted from the filament reach the anode 113, and X-rays are emitted from the anode 113. The emitted X-rays irradiate the subject 101 disposed between the X-ray detector 104 and the X-ray tube 103. The X-rays that have passed through the subject 101 are detected by the X-ray detector 104.

[0022] The timing at which the tube voltage control unit 102 starts applying the tube voltage pulse (the rising timing of the tube voltage pulse) and the timing at which the application of the tube voltage pulse ends (the falling of the tube voltage pulse) are instructed by the pulse width control unit 109 outputting timer signals Ton and Toff to the tube voltage control unit 102, respectively. The tube voltage control unit 102 applies the tube voltage pulse by starting and then blocking the application of the tube voltage pulse according to this timer signal.

[0023] In this way, a tube voltage pulse is applied between the filament 114 and the anode 113. When thermoelectrons reach the anode 113 from the filament 114, a tube current flows between the anode 113 and the filament 114. A tube current detector 106 is arranged in the wiring between the filament 114 and the tube voltage control unit 102 to detect the tube current. The tube current detector 106 can have any configuration. For example, a configuration that detects the tube current by detecting the magnetic field formed by the tube current flowing through the wiring can be used. The tube current detector 106 can also be arranged in the wiring between the anode 113 and the tube voltage control unit 102.

[0024] The pulse width control unit 109 includes an integrator 111 and a comparator 110. The comparator 110 outputs a timer signal Ton to the tube voltage control unit 102 to instruct the start of application of the tube voltage pulse at the pulse rate set by the control unit 112. When the comparator 220 outputs the timer signal Ton for the start of application, the integrator 111 integrates the tube current measured by the tube current detector 106 to calculate the tube current time integral (mAs / Flame). The comparator 110 determines whether the value of the tube current time integral calculated by the integrator 111 has reached the target tube current time integral value received from the control unit 112. If it has reached, the comparator 110 outputs a timer signal Toff to instruct the end of application of the tube voltage pulse.

[0025] The input unit 117 receives input of desired fluoroscopy conditions (target tube voltage value, target average tube current value (see Fig. 2(a)), pulse rate) from the user.

[0026] The X-ray detector 104 includes a plurality of two-dimensionally arranged X-ray detection elements and a readout circuit. The X-ray detection elements detect the incident X-rays and convert them into detection signals. The readout circuit is a circuit that reads out the detection signals of the X-ray detection elements. For example, a flat panel detector (FPD) can be used as the X-ray detector 104.

[0027] As shown in FIG. 2(f), in the X-ray detector 104, the readout time and the detection integration time are preset within one cycle of the pulse rate. For example, the readout time is a predetermined fixed time, and the remaining time of one cycle of the pulse rate is set as the integration time. The X-ray detection element integrates and detects the X-rays that reach the X-ray detection element within the integration time and converts them into detection signals. The readout circuit reads out the detection signals integrated and detected within the integration time at the readout time within the same cycle as the integration time and outputs them to the image processing unit 115.

[0028] The image processing unit 115 receives, from the readout circuit, the detection signals integrated and detected by the X-ray detection element in one cycle of the pulse rate, generates one X-ray image, and causes it to be displayed on the monitor 116. As a result, one X-ray image is displayed on the monitor 116 for each cycle of the pulse rate. By repeating this at the frequency of the pulse rate (for example, 4 to 30 fps), X-ray images of a moving image are displayed.

[0029] The control unit 112 receives the target tube voltage value (kV), the target average tube current value (mA), and the pulse rate (fps) from the input unit 117, and sets the target tube voltage value in the tube voltage control unit 102. Further, the control unit 112 sets a predetermined filament current value in the filament heater 107. Furthermore, the control unit 112 calculates the value of the target tube current time product from the target average tube current value and the pulse rate. The control unit 112 sets the calculated tube current time product and the pulse rate in the comparator 110 of the pulse width control unit 109.

[0030] Also, the image processing unit 115 may be configured to have a known automatic adjustment function that obtains the target tube voltage value, the target average tube current value, and the pulse rate by a predetermined mathematical formula or the like based on the luminance value of the generated X-ray image. When the automatic adjustment function is on, the control unit 112 is configured to receive the target tube voltage value, the target average tube current value, and the pulse rate from the image processing unit 115.

[0031] Hereinafter, the operation of the X-ray fluoroscopy apparatus according to the present embodiment will be described using the flow of FIG. 3.

[0032] <Step 11> If the control unit 112 receives an instruction to start fluoroscopy from the input unit 117, the control unit 112 receives a target tube voltage value (kV), a target average tube current value (mA) (see Fig. 2(a)), and a pulse rate (fps) from the input unit 117 or the image processing unit 115.

[0033] <Step 12> The control unit 112 outputs and sets the target tube voltage value (kV) to the tube voltage control unit 102.

[0034] <Step 13> Based on the target tube voltage value (kV) and the target average tube current value (mA), the control unit 112 refers to a predetermined table or calculation formula to obtain a filament current value (If), and outputs it to the filament heater 107. The filament heater 107 supplies the current of the filament current value (If) received from the control unit 112 to the filament 114 and starts heating (Fig. 2(b)).

[0035] The temperature of the filament 114 gradually rises from the time when the filament current starts (see Fig. 2(c)). The filament 114 emits thermoelectrons from the time when the supply of the filament current starts, and the amount of thermoelectrons emitted depends on the filament temperature.

[0036] <Step 14> The control unit 112 calculates a target tube current time product (mAs / Flame) value from the target average tube current value and the pulse rate. The target tube current time product is output to and set in the pulse width control unit 109 together with the pulse rate.

[0037] <Step 15> The pulse width control unit 109 outputs a timer signal Ton to the tube voltage control unit 102. The tube voltage control unit 102 starts applying the tube voltage at the timing when it receives the timer signal Ton (see Fig. 2(e)).

[0038] As a result, the thermoelectrons of the filament 114 reach the anode 113, and a tube current flows between the anode 113 and the filament 114 (Fig. 2(d)). Also, the emission of X-rays from the anode 113 is initiated.

[0039] <Step 16> The tube current detector 106 detects the tube current (mA) flowing through the wiring between the filament 114 and the tube voltage control unit 102, and outputs it to the integrator 111 of the pulse width control unit 109.

[0040] <Step 17> The integrator 111 of the pulse width control unit 109 calculates the tube current time integral by integrating the tube current received from the tube current detector 106. When the tube current time integral calculated by the integrator 111 reaches the target tube current time integral (mAs / Flame) set by the control unit 112, the comparator 110 outputs the timer signal Toff to the tube voltage control unit 102, instructing it to instantaneously cut off the tube voltage. However, if the end timing of the integration time of the X-ray detector 104 within one cycle occurs before the tube current time integral calculated by the integrator 111 reaches the target tube current time integral (mAs / Flame) set by the control unit 112, at that time, the comparator 110 outputs the timer signal Toff to the tube voltage control unit 102 (Fig. 2(f)). The tube voltage control unit 102 cuts off the tube voltage at the timing when it receives the timer signal Toff, and the application of one tube voltage pulse ends (Fig. 2(e)).

[0041] <Step 18> After the integration time within one cycle ends, the X-ray detector 104 reads out the detection signal of the X-ray detection element at the readout time and outputs it to the image processing unit 115 (Fig. 2(f)). The image processing unit 115 generates an X-ray image of one frame and displays it on the monitor 116. The control unit 112 returns to step 14 at the start timing of the next cycle of the pulse rate. When the condition of the target average tube current value is changed, the control unit 112 changes the target tube current-time product, starts applying the tube voltage pulse of the next cycle, and repeats steps 14 to 18 until an instruction to end fluoroscopy is input from the input unit 117.

[0042] Each time it repeats, since the pulse width of the tube voltage pulse is controlled so that the tube current-time product reaches the target tube current-time product, the luminance of the image generated in step 18 can be kept constant.

[0043] As a result, even when the temperature rise curve of the filament 114 changes due to environmental changes such as the ambient temperature, a display image with a desired luminance can be displayed from the start of fluoroscopy.

[0044] <<Embodiment 2>> The X-ray fluoroscopy apparatus according to Embodiment 2 will be described with reference to FIGS. 4 to 5.

[0045] FIG. 4 is a block diagram showing the configuration of the X-ray fluoroscopy apparatus according to Embodiment 2. FIG. 5 is a flowchart for explaining the operation of the X-ray fluoroscopy apparatus.

[0046] The configuration of the pulse width control unit 109 of the X-ray fluoroscopy apparatus according to Embodiment 2 is different from that of the X-ray apparatus according to Embodiment 1. Since the other configurations are the same as those in Embodiment 1, the description thereof will be omitted.

[0047] The pulse width control unit 109 according to Embodiment 2 includes an arithmetic unit 210 that obtains, by calculation, the cutoff timing of the tube voltage pulse based on the tube current measured by the tube current detector 106 immediately after the start of application of the tube voltage pulse. Specifically, the arithmetic unit 210 divides the target tube current-time product received by the control unit 112 by the tube current detected by the tube current detector 106 to obtain, by calculation, the time (pulse width) required to reach the target tube current-time product. The arithmetic unit 210 outputs a timer signal Toff to the tube voltage control unit 102 so as to cut off the obtained time of the tube voltage pulse.

[0048] The operation of the fluoroscopic X-ray apparatus according to Embodiment 2 will be described with reference to FIG. 5.

[0049] <Steps 11 to 15> Steps 11 to 15 are performed in the same manner as Steps 11 to 15 of Embodiment 1. As a result, the pulse width control unit 109 outputs a timer signal Ton to the tube voltage control unit 102, and the tube voltage control unit 102 starts applying the tube voltage at the timing when it receives the timer signal Ton.

[0050] <Step 21> The tube current detector 106 measures the tube current (mA) flowing through the wiring between the filament 114 and the tube voltage control unit 102, and outputs it to the pulse width control unit 109. The arithmetic unit 210 of the pulse width control unit 109 divides the target tube current time integral received from the control unit 112 in Step 14 by the tube current measured by the tube current detector 106, thereby obtaining the time (pulse width) to reach the target tube current time integral by calculation.

[0051] <Step 22> The arithmetic unit 210 of the pulse width control unit 109 outputs a timer signal Toff to the tube voltage control unit 102 to instruct to cut off the tube voltage at the time point when the pulse width obtained in Step 21 is reached, starting from the time point when the timer signal Ton is output in Step 15 to start applying the tube voltage pulse. However, when the pulse width calculated by the arithmetic unit 210 in Step 21 is larger than the integration time of the X-ray detector 104, a timer signal Toff for instructing to cut off the tube voltage at the end timing of the integration time is output to the tube voltage control unit 102. The tube voltage control unit 102 cuts off the tube voltage at the timing instructed by the timer signal Toff, and the application of one tube voltage pulse ends. As a result, the time integral of the tube current flowing through the X-ray tube 103 can be adjusted to the target tube current time integral.

[0052] <Step 18> The X-ray detector 104 reads out the detection signal of the X-ray detection element at the readout time and outputs it to the image processing unit 115. The image processing unit 115 generates an X-ray image of one frame and displays it on the monitor 116. The control unit 112 returns to step 14 at the start timing of the next cycle of the pulse rate and repeats steps 14 to 18.

[0053] Each time it repeats, since the pulse width of the tube voltage pulse is controlled so that the tube current-time product reaches the target tube current-time product, the luminance of the image formed in step 18 can be kept constant.

[0054] The X-ray fluoroscope of Embodiment 2 has an advantage that the configuration of the pulse width control unit 109 can be simplified as compared with the X-ray fluoroscope of Embodiment 1 because the pulse width is calculated by calculation. Other effects are the same as those of Embodiment 1.

[0055] <<Embodiment 3>> The X-ray fluoroscope of Embodiment 3 will be described with reference to FIGS. 6 to 8.

[0056] FIG. 6 is a block diagram showing the configuration of the X-ray fluoroscope of Embodiment 3. FIGS. 7(a) to (d) show the target average tube current, filament current, filament temperature, tube current, and tube voltage, respectively. FIG. 8 is a flow for explaining the operation of the X-ray fluoroscope.

[0057] In the fluoroscopic X-ray apparatus according to Embodiment 1, as shown in FIGS. 2(a) and 2(b), even when the target average tube current value is changed by the user or the image processing unit 115, the filament current is set to a predetermined constant current value. In the fluoroscopic X-ray apparatus according to Embodiment 3, the filament current value is also controlled according to the target average tube current value set by the user. As a result, while keeping the tube current-time product constant, the pulse width of the tube voltage pulse can be kept approximately constant, so that operation in a wider range of X-ray conditions becomes possible. However, due to the tube voltage rise time, control delay, etc., stable control is difficult with a pulse width below a certain level, so it is necessary to set it to a pulse width equal to or greater than a predetermined value. Also, the pulse width needs to be set to a value exceeding the integration time shown in FIG. 2(f). Therefore, the apparatus configuration of the fluoroscopic X-ray apparatus according to Embodiment 3 is the same as that of the fluoroscopic X-ray apparatus of FIG. 1 according to Embodiment 1, but includes a filament control unit 132 that controls the filament heater 107 within the control unit 112. In this regard, the apparatus according to Embodiment 3 is different from that according to Embodiment 1.

[0058] The filament control unit 132 receives the target average tube current value from the connected input unit 117 or image processing unit 115, determines the filament current value to be supplied to the filament 114 according to the received target average tube current value, and outputs it to the filament heater 107.

[0059] Thereby, as shown in FIG. 7(b), the filament current value is changed.

[0060] Hereinafter, the operation of the fluoroscopic X-ray apparatus according to Embodiment 3 will be described using the flowchart of FIG. 8.

[0061] <Steps 11 - 12> In Steps 11 - 12, the control unit 112, in the same manner as in Embodiment 1, receives the target tube voltage value (kV), the target average tube current value (mA) (see FIG. 7(a)), and the pulse rate (fps), outputs the target tube voltage value (kV) to the tube voltage control unit 102, and sets it.

[0062] <Step 31> Based on the target tube voltage value and the target average tube current value (mA) received in Step 11, the control unit 112 refers to a predetermined table or calculation formula to obtain the filament current value (If), and outputs it to the filament heater 107. The filament heater 107 supplies the current of the filament current value (If) received from the control unit 112 to the filament 114 and starts heating (Fig. 7(b)).

[0063] <Steps 14 - 18> In the X-ray fluoroscopy apparatus according to Embodiment 3, Steps 14 - 18 are performed in the same manner as Steps 14 - 18 in Embodiment 1.

[0064] In Embodiment 3, after the end of Step 18, the control unit 112 returns to Step 31 and repeats Steps 31, 14 - 18. If the condition of the target average tube current value is changed in Step 31, the filament current value is changed.

[0065] Thereby, even when the temperature rise curve of the filament 114 changes due to environmental changes such as the ambient temperature, a display image with a desired luminance can be displayed from the start of fluoroscopy.

Explanation of Reference Numerals

[0066] 14 Filament 21 Embodiment 101 Subject 102 Tube Voltage Control Unit 103 X-ray Tube 103 Anode 103a Container 104 X-ray Detector 106 Tube Current Detector 107 Filament Heater 109 Pulse Width Control Unit 110 Comparator 111 Integrator 112 Control Unit 113 Anode 114 Filament 115 Image Processing Unit 116 Monitor 117 Input section 132 Filament control section 210 Arithmetic section 220 Comparator

Claims

1. An X-ray tube including a filament as a cathode and an anode, a filament heater for supplying a current to heat the filament, a tube voltage control unit for applying a tube voltage pulse between the filament and the anode at a set pulse rate, a tube current detector, and a pulse width control unit, wherein the tube current detector measures a tube current flowing between the filament and the anode after the start of application of one of the tube voltage pulses, and the pulse width control unit determines a cutoff timing of the tube voltage pulse for causing a tube current time integral during which the tube voltage pulse is applied to reach a predetermined value based on the value of the tube current measured by the tube current detector, and instructs the tube voltage control unit to cut off the application of the tube voltage at the determined cutoff timing, thereby adjusting the pulse width of the tube voltage pulse for each pulse. An X-ray fluoroscopy apparatus characterized by the above.

2. The X-ray fluoroscopy apparatus according to Claim 1, wherein the pulse width control unit includes an integrator, the integrator calculates a time integral of the tube current measured by the tube current detector from the timing when the tube voltage control unit starts to apply one of the tube voltage pulses, and when the time integral of the tube current reaches the predetermined value, the pulse width control unit instructs the tube voltage control unit to cut off the application of the tube voltage. An X-ray fluoroscopy apparatus characterized by the above.

3. The X-ray fluoroscopy apparatus according to Claim 1, wherein the pulse width control unit obtains the cutoff timing of the tube voltage pulse by calculation based on the tube current measured by the tube current detector, and instructs the tube voltage control unit to cut off the application of the tube voltage at the obtained cutoff timing. An X-ray fluoroscopy apparatus characterized by the above.

4. The X-ray fluoroscopy apparatus according to Claim 1, further including an X-ray detector and an image processing unit, wherein the X-ray detector includes an X-ray detection element for detecting X-rays irradiated from the X-ray tube and passing through a subject and converting them into a detection signal, and a readout circuit for reading out the detection signal of the X-ray detection element, a detection integration time and a readout time are preset in the X-ray detector within a period of the pulse rate, the X-ray detection element integrates and detects X-rays reaching the detection element during the integration time and converts them into the detection signal, and the readout circuit reads out the detection signal integrated and detected during the integration time within the readout time and outputs it to the image processing unit. Before the cutoff timing, when the integration time ends before the cutoff timing, at the timing when the integration time ends, the pulse width control unit instructs the tube voltage control unit to cut off the application of the tube voltage. An X-ray fluoroscopy apparatus characterized by the above.

5. The X-ray fluoroscopy apparatus according to claim 1, further comprising a filament control unit that controls the filament heater. The filament control unit receives a target tube current value from a connected input unit or image processing unit, determines a filament current value to be supplied to the filament according to the received target tube current value, and outputs it to the filament heater. The filament heater supplies a filament current of the filament current value received from the control unit to the filament. An X-ray fluoroscopy apparatus characterized by the above.

6. An X-ray fluoroscopy apparatus having an X-ray tube including a filament as a cathode and an anode, and a filament heater that supplies a current for heating the filament, and performing pulsed fluoroscopy by applying a tube voltage pulse between the filament and the anode at a set pulse rate. A control method for the apparatus, After the start of the application of one of the tube voltage pulses, measure the tube current flowing between the filament and the anode. Based on the measured value of the tube current, determine the cutoff timing of the tube voltage pulse for reaching a predetermined value of the tube current time integral while the tube voltage pulse is being applied, and cut off the application of the tube voltage at the determined cutoff timing, thereby adjusting the pulse width of the tube voltage pulse for each pulse. A control method for an X-ray fluoroscopy apparatus characterized by the above.

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