X-ray tube apparatus and X-ray apparatus

Abstract

To provide an X-ray tube device and an X-ray device that have a simple structure and can detect deterioration and predict the lifespan of the X-ray tube device. [Solution] The X-ray tube apparatus 1 comprises a cathode 10 having a filament 12 that emits electrons and a focusing body 14 that focuses the emitted electrons, an anode 20 that emits X-rays when electrons emitted from the filament 12 are incident on it, a vacuum enclosure 30 that encloses the cathode 10 and the anode 20 and maintains a vacuum inside, a first power supply 40 that applies a tube voltage between the cathode 10 and the anode 20, a second power supply 50 that passes a tube current through the filament 12 and heats the filament 12, a third power supply 60 that lowers the potential of the focusing body 14 relative to the potential of the filament 12, and an ammeter 70 that detects the current caused by ionized positive ions flowing through the focusing body 14, which are positive ions ionized inside the vacuum enclosure 30.

Description

Technical Field

[0001] The present invention relates to an X-ray tube device and an X-ray device equipped with the X-ray tube device.

Background Art

[0002] An X-ray device equipped with an X-ray tube device is widely used in the medical field for X-ray fluoroscopy devices and X-ray imaging devices, etc., and also in the industrial field for defect inspection and foreign object inspection of various products, etc.

[0003] The X-ray tube device collides electrons emitted from the cathode with the anode in order to generate X-rays. In order to collide the electrons generated from the cathode with the anode, a high voltage of several hundred thousand volts is applied between the cathode and the anode. Therefore, the inside of the X-ray tube is kept in a vacuum to enhance insulation.

[0004] The parts inside the X-ray tube and the X-ray tube are sufficiently degassed so as to be in a high vacuum, but the degree of vacuum inside the tube gradually deteriorates due to the use and the number of years of the X-ray tube. When the degree of vacuum deteriorates, the X-ray tube has more discharges, which hinders the inspection. In many cases, tube replacement is often carried out after frequent arcing, or replacement is also often carried out when there is sufficient margin. Therefore, it is desirable to replace the tube in advance when the degree of vacuum starts to deteriorate and just before it hinders the inspection.

[0005] Conventionally, as a technique for measuring the degree of vacuum inside an X-ray tube, the technique described in Patent Document 1 is known. [[ID=2,6]]

[0006] In the X-ray tube device described in Patent Document 1, when generating X-rays, a voltage is applied so that the potential of the anode becomes higher than that of the cathode in order to collide the electrons emitted from the filament of the cathode with the anode. On the other hand, when measuring the degree of vacuum, a voltage is applied so that the potential of the anode becomes lower than that of the cathode in order to measure the current due to the positive ions of the trace amount of gas inside the X-ray tube, and a minute current due to the positive ions flowing into the cathode is detected, and the degree of vacuum inside the X-ray tube is measured based on the current value of the detected current.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-146288 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The X-ray tube apparatus described in Patent Document 1 has a first circuit in parallel for applying a voltage to the cathode so that the anode potential is high, and a second circuit in parallel for applying a voltage to the cathode so that the anode potential is low. It also has many switches, including a switch for switching the first circuit and the second circuit on and off during X-ray generation and vacuum level measurement, which results in a complex structure.

[0009] This invention has been made in view of these circumstances, and aims to provide an X-ray tube device and an X-ray device that can detect deterioration and predict the lifespan of an X-ray tube device with a simple structure. [Means for solving the problem]

[0010] The invention according to the first aspect is an X-ray tube apparatus comprising: a cathode having an electron source that emits electrons and a focusing body that focuses electrons emitted from the electron source; an anode provided opposite the cathode and emitting X-rays when electrons emitted from the electron source are incident on it; a vacuum enclosure enclosing the cathode and anode and maintaining a vacuum inside; a first power supply that applies a tube voltage between the cathode and anode; a second power supply that passes a tube current through the electron source and heats the electron source; a third power supply that lowers the potential of the focusing body relative to the potential of the electron source; and an ammeter that detects a current caused by ionized positive ions flowing through the focusing body.

[0011] According to a first aspect of the present invention, there is no need to provide a switch between the cathode focuser and the electron source for vacuum level measurement, and the current due to positive ions flowing through the focuser can be detected simply by applying a voltage with a simple structure. Furthermore, the positive ion current value flowing through the focuser can be used to detect deterioration of the X-ray tube apparatus (detection of vacuum level deterioration) and predict its lifespan. In addition, the positive ion current value can be detected during X-ray generation.

[0012] In the first embodiment, the X-ray tube apparatus according to the second aspect of the present invention is such that the electron source is a filament, and the second power supply is a device that heats the filament to generate thermionic electrons from the filament.

[0013] In the X-ray tube apparatus according to the third aspect of the present invention, in the first or second aspect, the negative terminal of the first power supply is preferably connected to an electron source and to the positive terminal of the third power supply, the positive terminal of the first power supply is preferably connected to the anode, and the negative terminal of the third power supply is preferably connected to a focusing body via an ammeter.

[0014] In the X-ray tube apparatus according to the fourth aspect of the present invention, in the third aspect, it is preferable that the positive terminal of the first power supply and the anode, and the vacuum enclosure, are grounded.

[0015] In the X-ray tube apparatus according to the fifth aspect of the present invention, in the first or second aspect, the first power supply comprises a fourth power supply and a fifth power supply, the negative terminal of the fourth power supply is connected to an electron source and to the positive terminal of the third power supply, the negative terminal of the third power supply is connected to a focusing body via an ammeter, the positive terminal of the fourth power supply is connected to the negative terminal of the fifth power supply, the positive terminal of the fifth power supply is connected to the anode, and it is preferable that the space between the positive terminal of the fourth power supply and the negative terminal of the fifth power supply, and the vacuum enclosure, are each grounded.

[0016] The X-ray tube device according to the sixth aspect of the present invention preferably includes, in any one of the first to fifth aspects, a degree-of-vacuum measuring device that measures the degree of vacuum inside the vacuum envelope based on the current value of the current due to positive ions detected by an ammeter. By measuring the degree of vacuum inside the vacuum envelope, deterioration of the degree of vacuum inside the vacuum envelope can be detected.

[0017] The X-ray tube device according to the seventh aspect of the present invention, in the sixth aspect, the degree-of-vacuum measuring device measures the degree of vacuum during the X-ray generation period.

[0018] The invention according to the eighth aspect is an X-ray device equipped with an X-ray tube device according to any one of the first to seventh aspects.

Advantages of the Invention

[0019] According to the present invention, deterioration detection and life prediction of an X-ray tube device can be performed with a simple structure.

Brief Description of the Drawings

[0020] [Figure 1] [[ID=二十三]]Figure 1 is a schematic diagram showing a first embodiment of an X-ray tube device according to the present invention. [Figure 2] Figure 2 is a schematic diagram showing a second embodiment of an X-ray tube device according to the present invention.

Modes for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of an X-ray tube device and an X-ray device according to the present invention will be described with reference to the accompanying drawings.

[0022] [First Embodiment] Figure 1 is a schematic diagram showing a first embodiment of an X-ray tube device according to the present invention.

[0023] The X-ray tube in the X-ray tube device 1 shown in Figure 1 includes a cathode 10, an anode 20 provided opposite to the cathode 10, and a vacuum envelope 30 that encloses the cathode 10 and the anode 20 and maintains a vacuum inside.

[0024] The cathode 10 has a filament 12, which is an electron source that emits electrons, and a focuser 14 that focuses the electrons emitted from the filament 12. The anode 20 has a target that emits X-rays 90 when electrons (electron beams) emitted from the filament 12 are incident on it. The anode 20 may be either a rotating anode or a stationary anode, but in the rotating anode type X-ray tube apparatus 1, the actual area of ​​the target that collides with the electrons can be increased, and a large tube current can be passed.

[0025] Vacuum enclosures 30 can be made of glass tubes called valves or metal, and are used depending on the application and installation location.

[0026] Electrons emitted from the filament 12 of the cathode 10 collide with the target of the anode 20, generating X-rays. In order to generate X-rays, a high voltage must be applied between the cathode 10 and the anode 20 inside the vacuum enclosure 30, and therefore the inside of the vacuum enclosure 30 is a vacuum and airtight.

[0027] Furthermore, the X-ray tube apparatus 1 includes a power supply (first power supply 40) that applies a tube voltage between the cathode 10 and the anode 20, a power supply (second power supply 50) that passes a tube current through the filament 12 and heats the filament 12, and a power supply (third power supply 60) that lowers the potential of the focusing body 14 relative to the potential of the filament 12.

[0028] In this example, the first power supply 40 applies a voltage of approximately 140kV between the cathode 10 and the anode 20. The positive terminal of the first power supply 40 is connected to the anode 20, and the negative terminal of the first power supply 40 is connected to the cathode 10 (filament 12 and the positive terminal of the third power supply 60). Furthermore, the space between the positive terminal of the first power supply 40 and the anode 20, and the vacuum enclosure 30 are grounded to ground 80. Therefore, the anode 20 is at 0V, and the cathode 10 is at approximately -140kV.

[0029] In this example, the second power supply 50 applies a voltage of approximately 10V to the filament 12, causing a tube current to flow through the filament 12, heating the filament 12, and generating thermionic electrons.

[0030] The third power supply 60 provides a potential difference of about 300 V between the filament 12 and the focusing cup 14 in this example. The negative terminal of the third power supply 60 is connected to the focusing cup 14 via the ammeter 70, and the positive terminal of the third power supply 60 is connected to the negative terminal side of the first power supply 40.

[0031] Therefore, while the filament 12 is at about -140 kV, the focusing cup 14 is at -140.3 kV, and the potential of the focusing cup 14 is 300 V lower than that of the filament 12. In this example, a potential difference of about 300 V is provided between the filament 12 and the focusing cup 14, but the potential difference is not limited to about 30 V and can be, for example, 100 V or several hundred V.

[0032] It is needless to say that the first power supply 40, the second power supply 50, and the third power supply 60 are controlled by a controller (not shown) to supply power during the use of the X-ray tube device 1 and to stop the power supply during non-use.

[0033] The X-ray tube device 1 further includes an ammeter 70 and a vacuum gauge 100.

[0034] The ammeter 70 detects the current due to the positive ions ionized inside the vacuum envelope 30 and flowing into the focusing cup 14. The vacuum gauge 100 measures the degree of vacuum inside the vacuum envelope 30 based on the current value of the current due to the positive ions detected by the ammeter 70. Details of the measurement of the degree of vacuum by the vacuum gauge 100 will be described later.

[0035] <Operation of the X-ray tube device> When operating the X-ray tube device 1 configured as described above, power is supplied from the first power supply 40, the second power supply 50, and the third power supply 60 to each part. <00001​​When a voltage of approximately 10V is applied to the filament 12 by the second power supply 50, tube current flows through the filament 12. As a result, the filament 12 is heated, and thermionic electrons are emitted from the filament 12.

[0037] Thermionic electrons emitted from the filament 12 are focused by the focusing body 14. Thermionic electrons focused by the focusing body 14 are accelerated toward the anode 20 by a high voltage of approximately -140kV applied between the cathodes 10 and 20 by the first power supply 40, and collide with the target, which is the anode 20. X-rays 90 are emitted when these thermionic electrons collide with the target.

[0038] The X-rays 90 generated inside the X-ray tube are emitted to the outside through the radiation window (not shown) of the X-ray tube device 1 and used in X-ray devices such as X-ray fluoroscopy devices and X-ray imaging devices.

[0039] Incidentally, gases that degrade the vacuum level inside the vacuum enclosure 30 can be internal gases from components inside the vacuum enclosure 30 or slow leaks, and since these are major causes of arcing, they need to be monitored during use of the X-ray tube apparatus 1.

[0040] The gas inside the X-ray tube is ionized (also called dissociated) and floats within the tube. The positively ionized gases among the floating ionized gases are captured by the focusing element 14. The focusing element 14 has a potential approximately 300V lower than the potential of the filament 12, making it possible to capture positive ions.

[0041] The capture of cations by the focusing element 14 causes an electric current to flow through the focusing element 14, and the ammeter 70 detects the value of the electric current flowing through the focusing element 14.

[0042] The vacuum level measuring instrument 100 measures the vacuum level inside the vacuum enclosure 30 based on the current value of the current caused by positive ions detected by the ammeter 70.

[0043] Here, the degree of vacuum inside the vacuum enclosure 30 and the current value due to cations (cation current value) are proportionally related, as shown in the following equation.

[0044] [Mathematics 1] Vacuum level (Pa) = Correction factor α × Cation current value (A) In the above equation [Equation 1], the correction factor α is a value determined by the size, shape, etc., of the X-ray tube.

[0045] The vacuum level measuring instrument 100 measures the vacuum level (Pa) by multiplying the cation current value (A) detected by the ammeter 70 by a correction factor α, as shown in the above equation [Equation 1].

[0046] Thus, according to the X-ray tube apparatus 1 of the first embodiment, a switch or the like to switch between X-ray generation and vacuum measurement is not required between the filament 12 of the cathode 10 and the focusing body 14 for vacuum measurement. The vacuum can be measured by applying a voltage between the filament 12 and the focusing body 14 that lowers the potential of the focusing body 14 relative to the potential of the filament 12, and detecting the positive ion current flowing through the focusing body 14. This allows for vacuum measurement with a simple structure, and also allows for vacuum measurement during the X-ray generation period.

[0047] Furthermore, the vacuum level inside the vacuum enclosure 30 gradually deteriorates with use and the passage of time of the X-ray tube apparatus 1. Therefore, for example, by pre-determining the relationship between the elapsed time (usage time) of the X-ray tube apparatus 1 and the vacuum level inside the vacuum enclosure 30 measured by the vacuum level measuring instrument 100 for several X-ray tube samples from the X-ray tube apparatus 1, it is possible to predict the period until the vacuum level reaches its lifespan (lifespan) from the current vacuum level. Incidentally, if the measured vacuum level (Pa) is 1 × 10⁻⁶ -5 If the order of magnitude is below (Pa), there is no problem with discharge, but 1 × 10 -4 When the pressure exceeds (Pa), discharge problems arise.

[0048] Furthermore, degradation detection and lifespan prediction of X-ray tubes can be performed without measuring the vacuum level inside the vacuum enclosure 30. For example, data on the cation current value flowing through the focusing unit 14 and the elapsed time can be obtained in advance for multiple X-ray tube samples to determine the threshold for the lifespan of the X-ray tube. Then, by detecting the current cation current value (measurement time), the elapsed time (lifespan) until the cation current value reaches the threshold for the lifespan of the X-ray tube can be predicted.

[0049] [Second Embodiment] Figure 2 is a schematic diagram showing a second embodiment of the X-ray tube apparatus according to the present invention.

[0050] Furthermore, in the X-ray tube apparatus 2 shown in Figure 2, parts common to the X-ray tube apparatus 1 shown in Figure 1 are denoted by the same reference numerals, and their detailed explanations are omitted.

[0051] The X-ray tube apparatus 2 of the second embodiment shown in Figure 2 differs from the X-ray tube apparatus 1 of the first embodiment shown in Figure 1 in that it has a power supply (first power supply) that applies a high voltage between the cathode 10 and the anode 20.

[0052] In other words, the first power supply 40 of the X-ray tube apparatus 1 in the first embodiment applies a voltage of approximately 140kV between the cathode 10 and the anode 20 with a single power supply, while the first power supply of the X-ray tube apparatus 2 in the second embodiment is composed of two power supplies (a fourth power supply 42 and a fifth power supply 44) connected in series, and a voltage of approximately 140kV is applied between the cathode 10 and the anode 20 with these two power supplies.

[0053] Specifically, the fourth power supply 42 and the fifth power supply 44 each generate a voltage of approximately 70kV. The negative terminal of the fourth power supply 42 is connected to the filament 12 and the positive terminal of the third power supply 60. The positive terminal of the fourth power supply 42 is connected to the negative terminal of the fifth power supply 44, and the positive terminal of the fifth power supply 44 is connected to the anode 20.

[0054] Furthermore, the positive terminal of the fourth power supply 42 and the negative terminal of the fifth power supply 44, as well as the vacuum enclosure 30, are each grounded to the ground 80. Therefore, a voltage of approximately +70kV is applied to the anode 20, and a voltage of approximately -70kV is applied to the cathode 10, resulting in a total voltage of approximately 140kV being applied between the cathode 10 and the anode 20.

[0055] According to the X-ray tube apparatus 2 of the second embodiment, the same effects and advantages as the X-ray tube apparatus 1 of the first embodiment can be obtained. Furthermore, by configuring the first power supply that applies a high voltage between the cathode 10 and the anode 20 with two power supplies (a fourth power supply 42 and a fifth power supply 44), and by grounding the area between the positive terminal of the fourth power supply 42 and the negative terminal of the fifth power supply 44, and the vacuum enclosure 30, to ground 80, a voltage of about 140kV can be applied between the cathode 10 and the anode 20, and the potential of the anode 20 can be raised by about 70kV relative to the potential of the vacuum enclosure 30 (0V).

[0056] The present invention, as described above, is not limited to the X-ray tube apparatus of this embodiment, and various modifications are possible. In this embodiment, the invention is described in detail for clarity, and is not necessarily limited to having all the configurations described, and it goes without saying that this also includes cases in which the X-ray tube apparatus does not have a vacuum level measuring instrument.

[0057] Furthermore, while the ammeter can detect the cation current value during the X-ray generation period, the detection of the cation current value by the ammeter is not limited to continuous use during the X-ray generation period. For example, it may be performed at regular intervals, such as at certain usage times or at regular usage times.

[0058] Furthermore, X-ray devices such as X-ray fluoroscopy devices and X-ray imaging devices equipped with the X-ray tube device according to the present invention are not limited to devices used in the medical field, but may also be devices used in industrial fields such as product defect inspection and foreign object inspection.

[0059] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0060] 1, 2...X-ray tube device 10...Cathode 12… Filament 14…Focusing body 20...Anode 30...Vacuum envelope 40...1st power supply 42…4th power supply 44…5th power supply 50…Second power supply 60...Third power supply 70...Ammeter 80... Grand 90...X-ray 100...Vacuum measuring device

Claims

1. A cathode having an electron source that emits electrons and a focusing body that focuses electrons emitted from the electron source, An anode is provided opposite the cathode and emits X-rays when electrons emitted from the electron source are incident on it, A vacuum enclosure that encloses the cathode and anode and maintains a vacuum inside, A first power supply that applies a tube voltage between the cathode and the anode, A second power supply that passes tube current through the electron source and heats the electron source, A third power supply that lowers the potential of the focusing body relative to the potential of the electron source, An ammeter for detecting the current caused by ionized positive ions flowing through the focusing element, wherein the positive ions are ionized inside the vacuum enclosure. An X-ray tube apparatus equipped with [specific features / equipment].

2. The electron source is a filament, The second power supply heats the filament to generate thermionic electrons from the filament. The X-ray tube apparatus according to claim 1.

3. The negative terminal of the first power supply is connected to the electron source and the positive terminal of the third power supply. The positive terminal of the first power supply is connected to the anode, The negative terminal of the third power supply is connected to the focusing unit via the ammeter. The X-ray tube apparatus according to claim 1.

4. The positive terminal of the first power supply and the anode, and the vacuum enclosure, are each grounded. The X-ray tube apparatus according to claim 3.

5. The first power supply has a fourth power supply and a fifth power supply, The negative terminal of the fourth power supply is connected to the electron source and also connected to the positive terminal of the third power supply. The negative terminal of the third power supply is connected to the focusing body via the ammeter. The positive terminal of the fourth power supply is connected to the negative terminal of the fifth power supply. The positive terminal of the fifth power supply is connected to the anode, The area between the positive terminal of the fourth power supply and the negative terminal of the fifth power supply, and the vacuum enclosure, are each grounded. The X-ray tube apparatus according to claim 1.

6. The vacuum level measuring device is provided to measure the vacuum level inside the vacuum enclosure based on the current value of the current caused by the cations detected by the ammeter. The X-ray tube apparatus according to claim 1.

7. The vacuum level measuring instrument measures the vacuum level during the X-ray generation period. The X-ray tube apparatus according to claim 6.

8. An X-ray tube apparatus according to any one of claims 1 to 7 is installed. X-ray equipment.

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