X-ray generator, target adjustment method, and method of using X-ray generator

Abstract

An X-ray generating device comprises: an electron gun; and a target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays. The X-ray generating device comprises: a control unit that controls the execution of a first mode and a second mode; the first mode irradiates the target with an electron beam adjusted to a current within a first current range to thin the target; the second mode irradiates the target with an electron beam adjusted to a current within a second current range to generate X-rays. The lower limit of the first current range is greater than the upper limit of the second current range.

Description

Technical Field

[0001] The present invention relates to an X-ray generating device, a target adjustment method, and a method for using the X-ray generating device. Background Art

[0002] In a penetrating X-ray tube, an electron beam is irradiated onto a target, thereby radiating X-rays from the target. The electron beam generated at the cathode is accelerated by an accelerating voltage and irradiated onto the target. If the accelerating voltage is changed, the energy of the electron beam that collides with the target will change. In the case where the target is thinner than the optimal thickness, a portion of the electron beam will penetrate the target, so the amount of X-rays generated will decrease. On the other hand, in the case where the target is thicker than the optimal thickness, the generated X-rays will attenuate when penetrating the target. That is, the thickness of the target where the radiation amount of X-rays is the largest varies depending on the accelerating voltage. Therefore, for a single target, the range of the accelerating voltage is limited. In order to expand the range of the accelerating voltage, it is necessary to have multiple targets with different thicknesses.

[0003] Patent document 1 describes a transmission type X-ray tube device, which has: an X-ray transmission window; a metal film, forming an X-ray target provided on the vacuum side of the X-ray transmission window; an electron gun, generating an electron beam; and a deflector, deflecting the electron beam. The metal film has a gradually changing thickness. In the X-ray tube device, the electron beam is irradiated to a portion of the metal film where the thickness of the metal film is consistent with the depth of electron entry. However, the X-ray tube device has individual differences due to the processing accuracy of the metal film, the assembly tolerance of the X-ray tube device, etc., so it is difficult to accurately irradiate the electron beam to the target position of the metal film, that is, the position with the target film thickness. Therefore, the conventional X-ray tube device must have a special configuration or adjustment step for adjusting the incident position of the metal film with respect to the electron beam.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-126650 Summary of the invention

[0007] The present invention provides a technique that facilitates efficient generation of X-rays.

[0008] The first aspect of the present invention relates to an X-ray generating device, comprising: an electron gun; and a target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays, the X-ray generating device comprising: a control unit configured to control a first mode and a second mode; the first mode irradiates the target with an electron beam with a current adjusted to a first current range to thin the target; the second mode irradiates the target with an electron beam with a current adjusted to a second current range to generate X-rays. The lower limit of the first current range is greater than the upper limit of the second current range.

[0009] The second aspect of the present invention relates to an X-ray generating device, comprising: an electron gun; a target, configured to be irradiated with an electron beam emitted from the electron gun to thereby generate X-rays; and a deflector, configured to deflect the electron beam, in the X-ray generating device: the target has a plurality of recesses, the plurality of recesses are arranged at positions corresponding to a plurality of acceleration voltages applied between a cathode of the electron gun and the target, respectively, and the thickness of the target is different at the plurality of recesses.

[0010] A third aspect of the present invention relates to a method for adjusting the thickness of a target of an X-ray generating device, the X-ray generating device having: an electron gun; and the target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays, the method comprising: a thinning step of irradiating the target with an electron beam adjusted to a current within a first current range to thin the thickness of the target; and a detection step of detecting X-rays generated by irradiating the target with an electron beam adjusted to a current within a second current range. The lower limit of the first current range is greater than the upper limit of the second current range.

[0011] A fourth aspect of the present invention relates to a method for using an X-ray generating device, the X-ray generating device comprising: an electron gun; and a target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays, the method comprising: a thinning step of irradiating the target with an electron beam adjusted to a current within a first current range to thin the target; and a generating step of irradiating the target with an electron beam adjusted to a current within a second current range to generate X-rays. The lower limit of the first current range is greater than the upper limit of the second current range. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A diagram schematically showing the arrangement of an X-ray generating tube according to an embodiment.

[0013] Figure 2 A diagram schematically showing how an electron beam emitted from an electron gun collides with a target.

[0014] Figure 3 The operation of thinning the target with each deflection direction (ie, incident position) corresponding to the acceleration voltage is schematically shown.

[0015] Figure 4 A block diagram schematically showing the configuration of an X-ray generating device according to an embodiment.

[0016] Figure 5 A block diagram schematically showing the configuration of an X-ray imaging apparatus according to an embodiment.

[0017] Figure 6 A flowchart showing an operation example of the X-ray generator in relation to execution of the first mode (processing mode) and the second mode (X-ray generation mode).

[0018] Figure 7 This is a flowchart showing an example of the operation of the X-ray generator for adjusting the target thickness for one tube voltage (cathode potential).

[0019] Figure 8 A flowchart showing an operation example or a usage example of the X-ray generator.

[0020] Fig. 9A A diagram schematically showing a portion of an example of a configuration of an X-ray generator having a target processed in a processing mode.

[0021] Fig. 9B A diagram schematically showing a portion of an example of a configuration of an X-ray generator having a target processed in a processing mode.

[0022] Fig. 9C A diagram schematically showing a portion of an example of a configuration of an X-ray generator having a target processed in a processing mode. DETAILED DESCRIPTION

[0023] The following detailed description of the embodiments is made with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claims. Although a plurality of features are described in the embodiments, not all combinations of the plurality of features are necessary for the invention, and a plurality of features may be combined arbitrarily. In addition, in the accompanying drawings, the same reference numerals are assigned to the same or similar parts, and repeated descriptions are omitted.

[0024] Figure 1The cross-sectional configuration near the center of an X-ray generating tube XG of an embodiment is schematically shown. The X-ray generating device 1 can be configured as a transmission type X-ray generating device. The X-ray generating device 1 includes an X-ray generating tube XG. The X-ray generating tube XG includes an electron gun EG. In addition, the X-ray generating tube XG may include: a target 22 that generates X-rays by receiving an electron beam or electrons emitted from the electron gun EG. In one example, the X-ray generating tube XG may include: an insulating tube 10 having two open ends; an anode 20 that closes one of the two open ends of the insulating tube 10; and a closing member 30 that closes the other of the two open ends of the insulating tube 10. The anode 20 may include: a target 22; a target holding plate 21 that holds the target 22; and an electrode 23 that supports the target holding plate 21 and applies a potential to the target 22 through the target holding plate 21. The anode 20 may be maintained at a ground potential, for example. The other closing member 30 may be configured to hold the electron gun EG. The insulating tube 10, the anode 20 and the blocking member 30 may constitute a container defining a closed space. The closed space may be maintained in a vacuum or high vacuum.

[0025] The electron gun EG may include a cathode CT, an extraction electrode EE disposed between the cathode CT and the anode 20, and a focusing electrode CE disposed between the extraction electrode EE and the anode 20. The cathode CT releases electrons. An accelerating voltage is supplied between the cathode CT and the anode 20. The amount of electrons incident on the target 22 of the anode 20 per unit time, i.e., the current, is called a tube current, which depends on the extraction potential supplied to the extraction electrode EE. The focusing electrode CE focuses the electrons or electron beams released from the cathode CT. The focusing electrode CE may include a plurality of electrodes.

[0026] The X-ray generating device 1 may include a cathode potential supply unit 41 for supplying a cathode potential to the cathode CT. The cathode potential supply unit 41 may be understood as a component that supplies an acceleration voltage between the anode 20 that can be maintained at a ground potential and the cathode CT. The X-ray generating device 1 may include an extraction potential supply unit 42 for supplying an extraction potential to the extraction electrode EE. The extraction potential supply unit 42 may be understood as a component that supplies an extraction voltage between the cathode CT and the extraction electrode EE. The X-ray generating device 1 may include a focusing potential supply unit 43 for supplying a focusing potential to the focusing electrode CE. The focusing potential supply unit 43 may be understood as a component that supplies a focusing voltage between the cathode CT and the focusing electrode CE.

[0027] The X-ray generating device 1 may further include a deflector 50 for deflecting the electron beam emitted from the electron gun EG. The deflector 50 may be arranged on the outside of the X-ray generating tube XG. The deflector 50 may be arranged, for example, so that an imaginary plane VP3 spanning the deflector 50 is located between an imaginary plane VP1 including the electron beam incident surface of the target 22 (the surface facing the electron gun EG) and an imaginary plane VP2 including the distal surface of the electron gun EG (the surface on the target 22 side). The imaginary planes VP1, VP2, and VP3 may be defined as planes perpendicular to the central axis AX of the electron gun EG. The deflector 50 causes a magnetic field to act on the electron beam emitted from the electron gun EG, thereby deflecting the electron beam. The amount by which the deflector 50 deflects the electron beam may depend on the acceleration voltage.

[0028] The deflector 50 may be formed of a permanent magnet, an electromagnet, or a permanent magnet and an electromagnet. In one example, the deflector 50 may include a first magnet and a second magnet. The first magnetic pole (e.g., S pole) of the first magnet and the second magnetic pole (e.g., N pole) of the second magnet may be arranged to face each other across the insulating tube 10 or the X-ray generating tube XG. The deflector 50 may be formed of a single magnet arranged so that the magnetic pole faces the radial direction of the insulating tube 10 or the X-ray generating tube XG.

[0029] The electrode 23 is electrically connected to the target 22 and imparts a potential to the target 22. When electrons from the electron gun EG collide with the target 22, X-rays are generated. The X-rays generated by the target 22 penetrate the target holding plate 21 and are radiated to the outside of the X-ray generating tube XG. The anode 20 can be maintained at a ground potential, for example, but can also be maintained at other potentials. The target 22 is made of a metal material. The target 22 is preferably made of a material with a high melting point, such as tungsten, tantalum or molybdenum. These materials are beneficial for improving the efficiency of X-ray generation. The target holding plate 21 can be made of a material that is easily penetrated by X-rays, such as beryllium or diamond. The X-ray generating device 1 may further include: a tube current detection unit 44, which detects the amount of electrons of the target 22 incident on the anode 20 per unit time, that is, the tube current.

[0030] Figure 2 The diagram schematically shows a state in which the electron beam EB emitted from the electron gun EG collides with the target 22 . Figure 2 The electron gun EG and the target 22 are shown to be arranged close to each other. However, the electron gun EG and the target 22 may be arranged to be further apart. The electron beam EB emitted from the electron gun EG is deflected by the magnetic field generated by the deflector 50 and then incident on or collides with the target 22. The amount by which the electron beam EB is deflected, in other words, the incident position of the electron beam EB on the target 22 may depend on the magnetic field generated by the deflector 50 and the acceleration voltage.

[0031] At Figure 2In the figure, the electron beam EBa schematically represents the trajectory of the electron beam EB of the accelerating voltage (the voltage applied between the cathode CT and the anode 20) Va. The electron beam EBa enters the target 22 to a depth Da determined by the accelerating voltage Va. The electron beam EBb schematically represents the trajectory of the electron beam EB of the accelerating voltage Vb. The electron beam EBb enters the target 22 to a depth Db determined by the accelerating voltage Vb. The electron beam EBc schematically represents the trajectory of the electron beam EB of the accelerating voltage Vc. The electron beam EBc enters the target 22 to a depth Dc determined by the accelerating voltage Vc. Here, |Va|>|Vb|>|Vc|. da is the deflection amount of the electron beam EBa (the displacement of the incident position of the electron beam EB from the central axis AX), db is the deflection amount of the electron beam EBb, and dc is the deflection amount of the electron beam EBc. When the strength of the magnetic field generated by the deflector 50 remains equal, da <db<dc。

[0032] It is assumed that the thickness of the target 22 that enables the most efficient emission of X-rays under the given acceleration voltage is taken as the optimal thickness. In this case, if the thickness of the target 22 is thicker than the optimal thickness, the X-rays will be attenuated until they pass through the target 22. On the other hand, if the thickness of the target 22 is thinner than the optimal thickness, the conversion efficiency of the target 22 from the electron beam to the X-rays is reduced. Therefore, the optimal thickness depends on the acceleration voltage. And, as mentioned above, the deflection amount of the electron beam (the incident position of the electron beam on the target 22) also depends on the acceleration voltage. This means that the thickness of the target 22 can be adjusted for each deflection amount (i.e., the incident position) corresponding to the acceleration voltage.

[0033] Figure 3 The operation of thinning the target 22 for each deflection amount (i.e., incident position) corresponding to the acceleration voltage is schematically shown. As described above, the depth of the electron beam EB entering the target 22 is determined by the acceleration voltage. On the other hand, Joule heat is generated at the position where the electron beam EB is incident on the target 22, and the amount of the Joule heat is determined by the tube current depending on the extraction potential supplied to the extraction electrode EE. As described in detail later, the X-ray generating device 1 has: a first mode for irradiating the target 22 with an electron beam adjusted to a current within a first current range, thereby thinning the target 22; and a second mode for irradiating the target 22 with an electron beam adjusted to a current within a second current range, thereby generating X-rays. The lower limit of the first current range is greater than the upper limit of the second current range. The lower limit of the first current range may be, for example, more than 2 times, more than 3 times, more than 4 times, or more than 5 times the upper limit of the second current range. The first mode can be understood as a processing mode for adjusting the thickness of the target 22. The second mode can be understood as an X-ray generation mode for generating X-rays.

[0034] In the first mode (processing mode), the target 22 is thinned or the thickness of the target 22 is adjusted by evaporating the portion of the target 22 where the electron beam EB is incident by utilizing the Joule heat generated by irradiating the target 22 with the electron beam EB. In the present embodiment, the thickness of the target 22 can be adjusted to an optimal thickness with a set tube voltage in the first mode, and the target 22 can be irradiated with the electron beam EB with the set tube voltage in the second mode (X-ray generation mode). Thus, the electron beam EB can be irradiated to the position adjusted to the optimal thickness, so that X-rays can be generated efficiently. For each of the multiple tube voltages, that is, for each of the multiple positions of the target 22, the thickness of the target 22 is adjusted to the respective optimal thickness, so that each of the multiple tube voltages can efficiently generate X-rays.

[0035] At Figure 3 , schematically shows an example of adjusting the thickness of the target 22 to an optimal thickness at the positions where the acceleration voltage Va for the electron beam EBa, the acceleration voltage Vb for the electron beam EBb, and the acceleration voltage Vc for the electron beam EBc are respectively incident.

[0036] Figure 4 A block diagram schematically showing the configuration of an X-ray generating device 1 according to an embodiment. The X-ray generating device 1 may include, for example, an X-ray generating tube XG, a booster circuit 110, a driving circuit 40, and a control unit CNT. As described above, the X-ray generating tube XG may include: an electron gun EG; and a target 22, which is irradiated with an electron beam EB emitted from the electron gun EG to generate X-rays. The booster circuit 110 may boost a voltage supplied from the outside and supply the boosted voltage to the driving circuit 40. The booster circuit 110 may be understood as a part of the driving circuit 40.

[0037] The driving circuit 40 may include, for example, a cathode potential supply unit 41, an extraction potential supply unit 42, a focus potential supply unit 43, and a tube current detection unit 44. The control unit CNT may include, for example, a CPU and a memory storing a program. The CPU may operate in a manner that controls the driving circuit 40 according to the operation of the program. Alternatively, the control unit CNT may be configured, for example, as a PLD (short for programmable logic device) such as an FPGA (short for field programmable gate array) or an ASIC (short for application specific integrated circuit).

[0038] The control unit CNT can be assembled in the drive circuit 40. All or part of the control unit CNT may be arranged inside a housing (not shown) that accommodates the boost circuit 110, the drive circuit 40, and the X-ray generating tube XG, or may be arranged outside the housing. The control unit CNT may be arranged to control the execution of a first mode and a second mode; the first mode irradiates the target 22 with an electron beam EB adjusted to a current within a first current range, thereby thinning the target 22; the second mode irradiates the target 22 with an electron beam EB adjusted to a current within a second current range, thereby generating X-rays. In the case where the first mode does not need to be executed, the module for executing the first mode may be removed from the control unit CNT.

[0039] At Figure 5 , represents the configuration of an X-ray imaging device 200 according to an embodiment. The X-ray imaging device 200 may include: an X-ray generating device 1; and an X-ray detecting device 240, which detects X-rays XR emitted from the X-ray generating device 1 and penetrating the object 230. The X-ray detecting device 240 may further include a control device 210 and a display device 220. The X-ray detecting device 240 may include an X-ray detector 242 and a signal processing unit 244. The control device 210 may control the X-ray generating device 1 and the X-ray detecting device 240. All or part of the aforementioned control unit CNT may be assembled in the control device 210. The X-ray detector 242 may detect or image the X-rays XR emitted from the X-ray generating device 1 and penetrating the object 230. The signal processing unit 244 may process the signal output from the X-ray detector 242, and supply the processed signal to the control device 210. The control device 210 causes the display device 220 to display an image according to the signal supplied from the signal processing unit 244.

[0040] At Figure 6 , showing an operation example of the X-ray generating device 1 regarding execution of the first mode (processing mode) and the second mode (X-ray generating mode). Figure 6 The operation shown can be controlled by the control unit CNT. In step S601, the control unit CNT reads the designation of the mode. In step S602, the control unit CNT determines whether the designation of the mode read in step S601 is the first mode or the second mode. In the case where the designation is the first mode, step S603 is executed. In the case where the designation is the second mode, step S604 is executed. In addition, the modes that the control unit CNT can execute include other modes such as the third mode in addition to the first mode and the second mode.

[0041] In step S603, as a preparation for executing the first mode (processing mode), the control unit CNT sets the extraction potential supply unit 42 so as to generate a first extraction potential for causing a tube current within a first current range to flow. In step S604, as a preparation for executing the second mode (X-ray generation mode), the control unit CNT sets the extraction potential supply unit 42 so as to generate a second extraction potential for causing a tube current within a second current range to flow.

[0042] At Figure 7 , which shows an operation example of the X-ray generator 1 for adjusting the thickness of the target 22 for one tube voltage (cathode potential). In the case of adjusting the thickness of the target 22 for each of a plurality of tube voltages (cathode potentials), the operation example of the X-ray generator 1 for adjusting the thickness of the target 22 for each of a plurality of tube voltages (cathode potentials) can be performed for each tube voltage. Figure 7 The operation shown. Figure 7 The operation shown can be controlled by the control unit CNT. In step S701, the control unit CNT sets the cathode potential supply unit 41 so that the target tube voltage is generated. In the following steps S702 to S710, the tube voltage set in step S701 is maintained. In step S702, the control unit CNT sets the parameter Dmax used in the following processing to 0 or a value close to 0.

[0043] In step S703, the control unit CNT makes Figure 6 The operation shown in FIG. 1 is started, and the X-ray generating device 1 or the extraction potential supply unit 42 is set to the second mode (X-ray generating mode). In step S704, the control unit CNT emits an electron beam EB from the cathode CT, thereby emitting X-rays from the target 22. The control unit CNT then causes the X-ray detector configured to detect the X-ray to detect the X-ray and receives the detection result as Ddet. The X-ray detector can be used in the execution Figure 7 Before the operation shown in the figure, it is set at a position where it can detect the X-rays generated by the X-ray generating device 1 and can be connected to the control unit CNT in a manner that allows communication. As the X-ray detector, the following can be used: Figure 5 The X-ray detector 242 of the X-ray imaging apparatus 200 shown in FIG. Step S703 can be understood as a step of confirming the dose of X-rays emitted from the target 22 at the current tube voltage (in other words, the incident position of the electron beam EB on the target 22) and the thickness of the target 22 at the incident position.

[0044] In step S705, the control unit CNT calculates the change rate Δ of Ddet from Dmax. The formula for calculating the change rate Δ may be, for example, Δ=(Dmax-Ddet) / Dmax. Here, if the value of the change rate Δ is positive, it means that the change in the dose of X-rays caused by the processing (thinning) of the target 22 in the first mode (processing mode) has passed the peak value. On the other hand, if the value of the change rate Δ is negative, it means that the change in the dose of X-rays caused by the processing (thinning) of the target 22 in the first mode (processing mode) has not yet reached the peak value.

[0045] In step S706, the control unit CNT determines whether the value of the change rate Δ is greater than the determination reference value R, in other words, determines whether the thinning is completed. Figure 7 The operation shown ends, otherwise step S707 is executed. In this example, the judgment reference value R is a positive value, and the value of the change rate Δ becomes greater than the judgment reference value R, which means that the change in the X-ray dose caused by the processing (thinning) of the target 22 in the first mode (processing mode) has passed the peak value. In other words, the peak value of the X-ray dose is detected. The value of the judgment reference value R can be set arbitrarily in consideration of noise and detection errors, for example, it can be set to 0.01. The judgment reference value R is 0.01%, which means that the detected X-ray dose is reduced by 1% from the peak value. Here, the target 22 is thinned until the aforementioned formula and judgment reference value are satisfied, but the thinning of the target 22 may also be performed until other predetermined conditions are satisfied. Other predetermined conditions may be, for example, that the thickness of the target 22 at the incident position of the electron beam reaches the allowable range of the target film thickness.

[0046] In step S707, the control unit CNT determines whether Ddet is greater than Dmax. If Ddet is greater than Dmax, in step S708, the value of Dmax is replaced with the value of Ddet (ie, Dmax is updated).

[0047] In step S709, the control unit CNT makes Figure 6 The operation shown is started, and the X-ray generator 1 or the extraction potential supply unit 42 is set to the first mode (processing mode). In step S710, the control unit CNT irradiates the target 22 with the electron beam EB at a current adjusted to a first current range for processing (thinning) the target 22, thereby thinning the target 22 (at the incident position determined by the tube voltage for the target 22). Step S710 is executed for a preset time, and then steps S701 to S710 are repeated.

[0048] Figure 8 An operation example or a usage example of the X-ray generator 1 is shown. Figure 8The operation shown can be controlled by the control unit CNT. In step S801, the control unit CNT determines whether the X-ray generator 1 is used for general purposes, typically whether it is used for X-ray imaging. In the case where the X-ray generator 1 is used for general purposes, steps S802 to S805 are executed. On the other hand, in the case of adjusting the thickness of the target 22, step S806 is executed. Figure 7 The operation shown.

[0049] In step S802, Figure 6 The operation shown is started, and the X-ray generator 1 or the extraction potential supply unit 42 is set to the second mode (X-ray generation mode). In step S803, the control unit CNT sets the cathode potential supply unit 41 in such a manner that the tube voltage as the target is generated. In step S804, as a preparation for executing the second mode (X-ray generation mode), the control unit CNT sets the extraction potential supply unit 42 in such a manner that the second extraction potential that causes the tube current within the second current range to flow is generated. In step S805, the control unit CNT controls the cathode potential supply unit 41 in such a manner that the electron beam is radiated from the cathode CT according to an instruction from a host control device, such as the control device 210, thereby radiating X-rays from the target 22 on which the electron beam is incident.

[0050] At Fig. 9A , Fig. 9B , Fig. 9C , schematically shows a part of the configuration of the X-ray generating device 1 having the target 22 processed by the above-mentioned method. Fig. 9A In the example, the target 22 has a plurality of recesses 901. The plurality of recesses 901 are arranged at positions corresponding to a plurality of acceleration voltages applied between the cathode CT of the electron gun EG and the target 22, and the thicknesses of the target 22 in the plurality of recesses 901 are different from each other. Fig. 9A In the example, the plurality of recesses 901 are arranged to be separated from each other.

[0051] At Fig. 9B In the example, the target 22 also has a plurality of recesses 902. The plurality of recesses 902 are arranged at positions corresponding to a plurality of acceleration voltages applied between the cathode CT of the electron gun EG and the target 22, and the thicknesses of the target 22 in the plurality of recesses 902 are different from each other. Fig. 9B In the example, adjacent recesses 902 among the plurality of recesses 902 are configured to be partially coupled to each other at their peripheries.

[0052] At Fig. 9C In the example of FIG. 1 , the target 22 has an inclined surface 903 so as to have thicknesses adjusted at positions corresponding to the plurality of acceleration voltages.

[0053] In this embodiment, if the acceleration voltage in the first mode and the second mode is kept the same, the electron beam will be incident on the same position of the target, so the electron beam can be incident on the optimal position of the target 22 (the position having the thickness adjusted in the first mode). Therefore, according to this embodiment, it is not necessary to have a configuration or operation for adjusting the incident position of the electron beam on the target according to the acceleration voltage.

[0054] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are attached to disclose the scope of the invention.

[0055]

Explanation of symbols

[0056] 1: X-ray generator

[0057] EG:Electron Gun

[0058] XG: X-ray generating tube

[0059] CT: cathode

[0060] EE: Extraction Electrode

[0061] CE: Focusing Electrode

[0062] 10: Insulation tube

[0063] 20: Anode

[0064] 21: Target holding plate

[0065] 22: Target

[0066] 23: Electrode

[0067] 30: Closing member

[0068] 50: Deflector

[0069] AX: Center axis

[0070] EB:Electron beam

Claims

1. An X-ray generating device comprising: an electron gun; and a target, which is configured to be irradiated by the electron beam emitted from the electron gun to generate X-rays; the X-ray generating device comprises: The control unit is configured to control the execution of a first mode and a second mode; the first mode irradiates the target with an electron beam at a current adjusted within a first current range, thereby thinning the target; the second mode irradiates the target with an electron beam at a current adjusted within a second current range, thereby generating X-rays, The lower limit of the first current range is greater than the upper limit of the second current range.

2. The X-ray generating device according to claim 1, further comprising: a deflector configured to deflect the electron beam, wherein the incident position of the electron beam on the target varies according to an accelerating voltage applied between a cathode of the electron gun and the target, and The control unit thins the target in the first mode for each of a plurality of incident positions corresponding to a plurality of acceleration voltages.

3. The X-ray generating device according to claim 2, wherein: The control unit determines whether thinning of the target in the first mode is completed based on a dose of X-rays radiated from the target.

4. The X-ray generating device according to claim 3, wherein: The control unit determines whether thinning of the target in the first mode is completed based on a dose of X-rays radiated from the target in the second mode.

5. The X-ray generating device according to claim 4, wherein: In the first mode, the target is thinned by evaporating the portion of the target on which the electron beam is incident, and The control unit thins the target until a predetermined condition is satisfied while repeatedly thinning the target in the first mode and detecting a dose of X-rays radiated from the target in the second mode while maintaining the acceleration voltage at the acceleration voltage for thinning the target.

6. The X-ray generating device according to claim 5, wherein: The predetermined condition is detection of a peak value of a dose of X-rays radiated from the target.

7. The X-ray generating device according to claim 1, wherein: The lower limit of the first current range is not less than twice the upper limit of the second current range.

8. The X-ray generating device according to claim 1, wherein: The electron gun includes a cathode, an anode including the target, an extraction electrode disposed between the cathode and the anode, and a focusing electrode disposed between the extraction electrode and the anode, and The control unit sets the potential of the extraction electrode to a first potential in the first mode, and sets the potential of the extraction electrode to a second potential different from the first potential in the second mode.

9. A method for adjusting the thickness of a target of an X-ray generating device, the X-ray generating device comprising: an electron gun; and the target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays; the adjustment method comprising: a thinning step of irradiating the target with an electron beam at a current adjusted to be within a first current range, thereby thinning the target; and a detection step of irradiating the target with an electron beam with a current adjusted to be within a second current range to generate X-rays, and detecting the X-rays, in, A lower limit of the first current range is greater than an upper limit of the second current range.

10. The adjustment method according to claim 9, wherein: The thinning step and the detecting step are repeatedly performed until a dose of X-rays emitted from the target in the detecting step satisfies a predetermined condition.

11. The adjustment method according to claim 10, wherein: The predetermined condition is detection of a peak value of a dose of X-rays radiated from the target.

12. The adjustment method according to claim 9, wherein: The X-ray generating device further comprises: a deflector configured to deflect the electron beam. The incident position of the electron beam on the target varies according to the accelerating voltage applied between the cathode of the electron gun and the target. The thinning step and the detecting step are performed for each of a plurality of incident positions corresponding to a plurality of acceleration voltages, respectively.

13. The adjustment method according to claim 9, wherein: The lower limit of the first current range is not less than twice the upper limit of the second current range.

14. The adjustment method according to claim 9, wherein: The electron gun includes a cathode, an anode including the target, an extraction electrode disposed between the cathode and the anode, and a focusing electrode disposed between the extraction electrode and the anode, and In the thinning step, the potential of the extraction electrode is set to a first potential, and in the detection step, the potential of the extraction electrode is set to a second potential different from the first potential.

15. A method for using an X-ray generating device, the X-ray generating device comprising: an electron gun; and a target configured to be irradiated with an electron beam emitted from the electron gun to generate X-rays; the method comprising: a thinning step of irradiating the target with an electron beam at a current adjusted to be within a first current range, thereby thinning the target; and a generating step of irradiating the target with an electron beam by adjusting the current within a second current range, thereby generating X-rays, in, A lower limit of the first current range is greater than an upper limit of the second current range.

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