X-ray tube device and x-ray device

Abstract

Provided are an X-ray tube device and an X-ray device with which deterioration detection and lifetime prediction of the X-ray tube device can be performed with a simple configuration. An X-ray tube device (1) is provided with: 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 by incidence of electrons emitted from the filament (12); the cathode (10) and the anode (20) are packaged in the vacuum outer cover (30), and the interior of the vacuum outer cover (30) is kept vacuum; a first power source (40) that applies a tube voltage between the cathode (10) and the anode (20); a second power supply (50) that heats the filament (12) by causing a tube current to flow through the filament (12); a third power source (60) that reduces the potential of the focusing body (14) with respect to the potential of the filament (12); and a current meter (70) that detects a current caused by cations flowing through the focusing body (14), said cations being ionized inside the vacuum housing (30).

Description

Technical Field

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

[0002] X-ray devices equipped with X-ray tubes are widely used in the medical field for X-ray fluoroscopy and X-ray imaging, and in the industrial field for defect inspection and foreign object inspection of various products.

[0003] To generate X-rays, the X-ray tube apparatus causes electrons emitted from the cathode to collide with the anode. To enable this collision, a high voltage of hundreds of thousands of volts is applied between the cathode and anode. Therefore, the inside of the X-ray tube is kept a vacuum to improve insulation.

[0004] The components inside the X-ray tube and the tube itself undergo thorough degassing to achieve a high vacuum. However, with use and over the years, the vacuum level inside the tube gradually deteriorates. If the vacuum level deteriorates, arcing within the X-ray tube increases, affecting the examination. In most cases, the tube is replaced only after frequent arcing, or when there is still sufficient margin for error. Therefore, it is desirable to replace the tube before the vacuum level begins to deteriorate and affects the examination.

[0005] Previously, the technique for measuring the vacuum level inside an X-ray tube was described in Patent Document 1.

[0006] The X-ray tube device described in Patent Document 1 generates X-rays by applying a voltage to the cathode to increase the potential of the anode in order to make electrons emitted from the cathode filament collide with the anode. On the other hand, when measuring the vacuum level, a voltage is applied to the cathode to decrease the potential of the anode in order to measure the current caused by the cations of trace gases inside the X-ray tube bulb. The tiny current caused by the cations flowing into the cathode is detected, and the vacuum level inside the X-ray tube is measured based on the current value of the detected current.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-146288

[0008] The X-ray tube device described in Patent Document 1 has a first circuit and a second circuit connected in parallel. The first circuit is used to apply a voltage to the cathode to increase the potential of the anode, and the second circuit is used to apply a voltage to the cathode to decrease the potential of the anode. It also has multiple switches, including switches for switching the first circuit and the second circuit on / off when generating X-rays and measuring vacuum. Therefore, it has a complex structure. Summary of the Invention

[0009] The present invention was made in view of this situation, and its object is to provide an X-ray tube device and an X-ray device that can perform deterioration detection and life prediction of an X-ray tube device with a simple structure.

[0010] The invention involved in the first aspect is an X-ray tube device comprising: a cathode having an electron source for emitting electrons and a focusing body for focusing electrons emitted from the electron source; an anode disposed opposite to the cathode and emitting X-rays by incident on electrons emitted from the electron source; a vacuum enclosure encapsulating the cathode and anode and maintaining the interior as a vacuum; a first power source applying a tube voltage between the cathode and the anode; a second power source causing a tube current to flow through the electron source and heating the electron source; a third power source causing the potential of the focusing body to decrease relatively relative to the potential of the electron source; and a galvanometer detecting the current caused by cations flowing through the focusing body, the cations being ionized inside the vacuum enclosure.

[0011] According to the first aspect of the present invention, it is not necessary to install a switch between the focusing element and the electron source of the cathode for measuring the vacuum level; the current caused by cations flowing through the focusing element can be detected simply by applying voltage with a simple structure. Furthermore, based on the value of the cation current flowing through the focusing element, it is possible to perform deterioration detection (vacuum level deterioration detection) and lifetime prediction of the X-ray tube device. Moreover, the cation current value can be detected during X-ray generation.

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

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

[0014] In the third embodiment, the X-ray tube device according to the fourth aspect of the present invention preferably has the positive terminal of the first power supply grounded between the positive terminal and the anode, and the vacuum casing grounded.

[0015] In the fifth aspect of the present invention, the X-ray tube device preferably includes a first power supply having a fourth power supply and a fifth power supply in the first or second aspect. 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 the focusing body via a galvanometer. 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 positive terminal of the fourth power supply and the negative terminal of the fifth power supply are grounded, and the vacuum casing is grounded.

[0016] In any of the first to fifth embodiments of the present invention, the X-ray tube apparatus according to the sixth embodiment preferably includes a vacuum level measuring device, which measures the vacuum level inside the vacuum chamber based on the current value of the current caused by cations detected by a galvanometer. By measuring the vacuum level inside the vacuum chamber, it is possible to detect a deterioration in the vacuum level inside the vacuum chamber.

[0017] In the seventh aspect of the present invention, the X-ray tube device, in the sixth aspect, involves a vacuum measuring device that measures the vacuum level during X-ray generation.

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

[0019] Invention Effects

[0020] According to the present invention, it is possible to perform deterioration detection and lifespan prediction of X-ray tube devices with a simple structure. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating a first embodiment of the X-ray tube apparatus according to the present invention.

[0022] Figure 2 This is a schematic diagram illustrating a second embodiment of the X-ray tube apparatus according to the present invention.

[0023] Symbol Explanation

[0024] 1, 2 - X-ray tube assembly, 10 - cathode, 12 - filament, 14 - focusing element, 20 - anode, 30 - vacuum enclosure, 40 - first power supply, 42 - fourth power supply, 44 - fifth power supply, 50 - second power supply, 60 - third power supply, 70 - ammeter, 80 - grounding terminal, 90 - X-ray, 100 - vacuum measuring device. Detailed Implementation

[0025] Hereinafter, preferred embodiments of the X-ray tube device and X-ray device according to the present invention will be described with reference to the accompanying drawings.

[0026] [First Implementation]

[0027] Figure 1 This is a schematic diagram illustrating a first embodiment of the X-ray tube apparatus according to the present invention.

[0028] Figure 1 The X-ray tube in the X-ray tube device 1 shown includes: a cathode 10; an anode 20 disposed opposite to the cathode 10; and a vacuum casing 30 that encapsulates the cathode 10 and the anode 20 and maintains the interior as a vacuum.

[0029] The cathode 10 has a filament 12 as an electron source for emitting electrons, and a focusing element 14 for focusing the electrons emitted from the filament 12. The anode 20 has a target material that emits X-rays 90 when electrons (electron beams) emitted from the filament 12 are incident on the target material. The anode 20 can be either a rotating anode or a fixed anode, but in the rotating anode type X-ray tube device 1, the actual area of ​​the target material colliding with the electrons can be increased, thereby allowing a larger tube current to flow.

[0030] Vacuum enclosure 30 has a glass tube or metal vacuum enclosure, which can be distinguished according to its purpose and installation location.

[0031] Electrons emitted from the filament 12 of the cathode 10 collide with the target material of the anode 20, thereby generating X-rays. In order to generate X-rays, a high voltage needs to be applied between the cathode 10 and the anode 20 inside the vacuum enclosure 30, thus the vacuum enclosure 30 becomes a vacuum-sealed state.

[0032] Furthermore, the X-ray tube apparatus 1 includes: a power supply (first power supply 40) for applying tube voltage between the cathode 10 and the anode 20; a power supply (second power supply 50) for causing tube current to flow through the filament 12 to heat the filament 12; and a power supply (third power supply 60) for relatively lowering the potential of the focusing body 14 relative to the potential of the filament 12.

[0033] In this example, the first power supply 40 applies a voltage of approximately 140 kV 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 positive terminal of the first power supply 40 and the anode 20 are grounded to grounding terminal 80, and the vacuum casing 30 is also grounded to grounding terminal 80. Therefore, the anode 20 is at 0V, and the cathode 10 is at approximately -140 kV.

[0034] In this example, the second power supply 50 applies a voltage of about 10V to the filament 12, causing tube current to flow through the filament 12 to heat the filament 12, thereby generating thermionic electrons.

[0035] In this example, the third power supply 60 sets a potential difference of about 300V between the filament 12 and the focusing body 14. The negative terminal of the third power supply 60 is connected to the focusing body 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.

[0036] Therefore, the filament 12 has a voltage of approximately -140kV, while the focusing element 14 has a voltage of -140.3kV. The potential of the focusing element 14 is only 300V lower than that of the filament 12. Furthermore, in this example, a potential difference of approximately 300V is set between the filament 12 and the focusing element 14, but the potential difference is not limited to approximately 300V; for example, it could be 100V or several hundredV.

[0037] Of course, the first power supply 40, the second power supply 50 and the third power supply 60 mentioned above are controlled by a controller (not shown) to supply power when the X-ray tube device 1 is in use and to stop supplying power when not in use.

[0038] The X-ray tube device 1 also includes a galvanometer 70 and a vacuum measuring device 100.

[0039] The galvanometer 70 detects the current generated by cations flowing through the focusing element 14, which are ionized inside the vacuum enclosure 30. The vacuum level measuring device 100 measures the vacuum level inside the vacuum enclosure 30 based on the current value generated by the cations detected by the galvanometer 70. Details of the vacuum level measurement performed by the vacuum level measuring device 100 will be described later.

[0040] <Operation of the X-ray Tube Device>

[0041] When operating the X-ray tube device 1 with the above-described structure, power is supplied to each part from the first power source 40, the second power source 50 and the third power source 60.

[0042] When a voltage of approximately 10V is applied to the filament 12 from 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.

[0043] Thermionic electrons emitted from filament 12 are focused by focusing element 14. These focused thermionic electrons are accelerated towards anode 20 and collide with the target material of anode 20 by a high voltage of approximately -140 kV applied between cathode 10 and anode 20 by first power supply 40. Upon collision with the target material, the thermionic electrons emit X-rays 90.

[0044] The X-rays 90 generated inside the X-ray tube are emitted to the outside from the radiation window (not shown) of the X-ray tube device 1 and used in X-ray devices such as X-ray fluoroscopy devices or X-ray imaging devices.

[0045] However, the gas that degrades the vacuum level inside the vacuum enclosure 30 may be internal gas of the components inside the vacuum enclosure 30 or slow leakage, which can be the main cause of arc discharge. Therefore, it is necessary to monitor it when using the X-ray tube device 1.

[0046] The gas inside the X-ray tube is ionized (also known as electrolysis) and floats within the tube. The cations in this floating ionized gas are replenished by the focusing element 14. The focusing element 14 has a potential approximately 300V lower than the filament 12, thus enabling the replenishment of cations.

[0047] Due to the supplementation of cations by the focusing element 14, the current caused by the cations flows through the focusing element 14, and the galvanometer 70 detects the current value of the current caused by the cations flowing through the focusing element 14.

[0048] The vacuum measuring device 100 measures the vacuum level inside the vacuum enclosure 30 based on the current value of the current caused by the cations detected by the ammeter 70.

[0049] Here, the vacuum level inside the vacuum enclosure 30 and the current value of the current induced by cations (cation current value) have a proportional relationship as shown in the following formula.

[0050] [Formula 1]

[0051] Vacuum degree (Pa) = Correction factor α × Cation current value (A)

[0052] In the above [Equation 1], the correction coefficient α is a value determined by the size, shape, etc. of the X-ray tube.

[0053] As shown in [Equation 1] above, the vacuum measuring device 100 measures the vacuum level (Pa) by multiplying the correction coefficient α by the cation current value (A) detected by the ammeter 70.

[0054] Thus, according to the X-ray tube apparatus 1 of the first embodiment, it is not necessary to install a switch between the filament 12 of the cathode 10 and the focusing body 14 for switching between generating X-rays and measuring vacuum in order to measure the vacuum degree. Instead, the vacuum degree can be measured by applying a voltage between the filament 12 and the focusing body 14 that reduces the potential of the focusing body 14 relative to the potential of the filament 12, and detecting the cation current flowing through the focusing body 14. Vacuum degree measurement can be performed with a simple structure, and the vacuum degree can be measured during X-ray generation.

[0055] Furthermore, as the X-ray tube device 1 is used and the number of years increases, the vacuum level inside the vacuum enclosure 30 gradually deteriorates. Therefore, for example, the relationship between the elapsed time (usage time) of the X-ray tube device 1 and the vacuum level inside the vacuum enclosure 30 measured by the vacuum level measuring device 100 can be determined in advance for multiple X-ray tube samples of the X-ray tube device 1, and the time required to reach the vacuum level of the lifetime (lifetime) can be predicted based on the vacuum level at the current moment. Incidentally, if the measured vacuum level (Pa) is 1×10 -5 Below the level of (Pa), there will be no discharge problem, but if it becomes 1×10-4 At levels above (Pa), discharge problems will occur.

[0056] Furthermore, even without measuring the vacuum level inside the vacuum chamber 30, it is possible to detect X-ray tube degradation and predict its lifespan. For example, by acquiring data on the cation current value flowing through the focusing element 14 and the elapsed time for multiple X-ray tube samples in advance, the threshold for reaching the lifespan of the X-ray tube can be determined. Then, by detecting the cation current value at the current moment (the measurement moment), the elapsed time (lifespan) required for the cation current value to reach the lifespan of the X-ray tube, i.e., the threshold, can be predicted.

[0057] [Second Implementation]

[0058] Figure 2 This is a schematic diagram illustrating a second embodiment of the X-ray tube apparatus according to the present invention.

[0059] In addition, Figure 2 In the X-ray tube device 2 shown, for the X-ray tube device 2 ... Figure 1 The common parts of the X-ray tube apparatus 1 shown are marked with the same symbols, and their detailed descriptions are omitted.

[0060] Figure 2 The X-ray tube device 2 of the second embodiment shown is... Figure 1 The difference between the X-ray tube apparatus 1 of the first embodiment shown is the power supply (first power supply) that applies a high voltage between the cathode 10 and the anode 20.

[0061] That is, in the first embodiment, the first power supply 40 of the X-ray tube device 1 applies a voltage of about 140kV between the cathode 10 and the anode 20 using a single power supply, but in the second embodiment, the first power supply of the X-ray tube device 2 is composed of two power supplies (the fourth power supply 42 and the fifth power supply 44) connected in series, and applies a voltage of about 140kV between the cathode 10 and the anode 20 using the two power supplies.

[0062] Specifically, the fourth power supply 42 and the fifth power supply 44 each generate a voltage of about 70kV. The negative terminal of the fourth power supply 42 is connected to the filament 12 and to 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.

[0063] Furthermore, the positive terminal of the fourth power supply 42 and the negative terminal of the fifth power supply 44 are grounded to the grounding terminal 80, and the vacuum enclosure 30 is also grounded to the grounding terminal 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, for a total voltage of approximately 140kV applied between the cathode 10 and the anode 20.

[0064] According to the X-ray tube device 2 of the second embodiment, the same operating effect as the X-ray tube device 1 of the first embodiment is obtained. Furthermore, by forming a first power supply with two power supplies (a fourth power supply 42 and a fifth power supply 44) to apply a high voltage between the cathode 10 and the anode 20, grounding the positive terminal of the fourth power supply 42 and the negative terminal of the fifth power supply 44 to the grounding terminal 80, and grounding the vacuum casing 30 to the grounding terminal 80, a voltage of about 140 kV can be applied between the cathode 10 and the anode 20, and the potential of the anode 20 can be increased by about 70 kV relative to the potential (0 V) of the vacuum casing 30.

[0065] The present invention described above is not limited to the X-ray tube apparatus of this embodiment, and may include various modifications. In this embodiment, the detailed description is for ease of understanding of the invention and is not limited to all described structures; for example, it certainly includes cases where the X-ray tube apparatus does not have a vacuum measuring device.

[0066] Furthermore, the galvanometer can detect the cation current value during X-ray generation, but is not limited to continuously detecting the cation current value based on the galvanometer during X-ray generation. For example, the above detection can also be performed at certain usage dates or at certain usage times.

[0067] Furthermore, X-ray devices such as X-ray fluoroscopy devices or X-ray imaging devices equipped with the X-ray tube device involved in this 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 or foreign object inspection.

[0068] Moreover, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

Claims

1. An X-ray tube device comprising: A cathode has an electron source that emits electrons and a focusing body that focuses the electrons emitted from the electron source; The anode is disposed opposite to the cathode and emits X-rays by incident of electrons emitted from the electron source; A vacuum enclosure, wherein the cathode and the anode are encapsulated within the vacuum enclosure, and the interior is maintained as a vacuum; The first power source applies a tube voltage between the cathode and the anode; The second power source allows tube current to flow through the electron source and heats the electron source. A third power source causes the potential of the focusing body to be relatively lower than the potential of the electron source; and A galvanometer detects the current caused by cations flowing through the focusing element, the cations being ionized inside the vacuum enclosure.

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

3. The X-ray tube apparatus according to claim 1 or 2, wherein, The negative terminal of the first power source is connected to the electron source and to the positive terminal of the third power source. The positive terminal of the first power supply is connected to the anode. The negative terminal of the third power source is connected to the focusing body via the ammeter.

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

5. The X-ray tube apparatus according to claim 1 or 2, wherein, The first power source has a fourth power source and a fifth power source. The negative terminal of the fourth power source is connected to the electron source and to the positive terminal of the third power source. 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 source is connected to the anode. The positive terminal of the fourth power supply is grounded with respect to the negative terminal of the fifth power supply, and the vacuum enclosure is also grounded.

6. The X-ray tube apparatus according to claim 1 or 2, wherein, The device is equipped with a vacuum measuring instrument, which measures the vacuum level inside the vacuum enclosure based on the current value of the current caused by the cation detected by the ammeter.

7. The X-ray tube apparatus according to claim 6, wherein, The vacuum level measuring device measures the vacuum level during X-ray generation.

8. An X-ray apparatus, wherein the X-ray tube apparatus of any one of claims 1 to 7 is mounted.

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