X-ray system and method

Abstract

An X-ray system is disclosed, comprising: an electron-impact X-ray source configured to generate an X-ray beam; a radiation-shielded housing having an X-ray outlet; an X-ray optical element arranged within the radiation-shielded housing, the X-ray optical element being configured to direct the X-ray beam towards the outlet; a shutter arranged at the outlet, the shutter being movable between an open position allowing X-rays to be output through the outlet and a closed position preventing X-rays to be output through the outlet; and a detector arranged to detect X-ray radiation directed from the X-ray source towards the outlet, wherein the detector is configured to detect X-ray radiation in a first energy range. A corresponding method of operating an X-ray system is also disclosed.

Description

Technical Field

[0001] This invention generally relates to X-ray systems. Background Technology

[0002] X-ray systems typically consist of an X-ray source and X-ray optics positioned to collect and guide the X-ray radiation generated by the X-ray source. Therefore, the amount of useful X-ray radiation obtainable from an X-ray system depends in part on the amount of radiation that can be collected by these optics. In this respect, existing technologies are limited by overall safety requirements and geometric constraints, which restrict how much of the generated radiation can be collected and used as the output of the X-ray system. Summary of the Invention

[0003] A typical prior art X-ray system includes an X-ray source with a shutter and X-ray optics for collecting the generated X-ray radiation and providing a useful output. It should be understood that more useful X-ray radiation can be obtained if the X-ray optics are positioned closer to the X-ray source. However, in the prior art, the minimum distance between the source and the optics depends on the internal geometry of the light source and the size of the shutter.

[0004] For safety reasons, a shutter is required; the shutter must protect the surrounding environment, especially humans, from accidental exposure to X-rays at any time. If the X-ray optics are not properly aligned when the source is turned on, radiation can be virtually ubiquitous. Therefore, in the prior art, the X-ray optics are positioned downstream of the shutter, which limits how short the distance between the source and the optics can be and thus how much useful X-ray radiation can be provided.

[0005] This invention provides a safe way to bring optics closer to a source by providing a radiation-shielding housing, preferably with only one intended X-ray exit. The housing can be an extension of the X-ray source's outer shell, or it can be rigidly or flexibly connected to the outer shell. It is even conceivable that the source and housing are disconnected from each other, provided that a radiation trap is present where they meet to prevent any leakage of X-ray radiation. This invention is particularly useful in electron-impact X-ray systems, where X-ray radiation is generated by the interaction between an electron beam and a target. The target can be a solid target, such as a reflective or transmissive target, or a liquid target, such as a liquid jet target.

[0006] The general idea underlying this invention is that if (multiple) X-ray optical elements are housed within a radiation-shielding housing and thus upstream of the shutter, these X-ray optical elements can be placed closer to the X-ray source, wherein the shutter, which prevents unintentional X-ray radiation output, is located at the outlet of the radiation-shielding housing. The X-ray optical elements are configured to direct X-ray radiation generated by the X-ray source toward the outlet. The radiation-shielding housing thus serves to prevent X-ray radiation leakage and allows output only through the outlet, while the shutter controls whether output through the outlet is permitted or prohibited.

[0007] Traditionally, the safety shutter is integrated with the X-ray source, i.e., built into it, and the X-ray optics and / or monochromator are arranged downstream of the safety shutter. Therefore, moving the safety shutter downstream of the optics / monochromator would seem counterintuitive to those skilled in the art. However, according to the present invention, this is made possible by a radiation-shielding housing in which the X-ray optics are housed.

[0008] Conveniently, one or more detectors can be provided within a radiation-shielding housing to detect X-ray radiation directed toward the exit. For example, the detector can be attached to a shutter on the side of its interior facing the radiation-shielding housing. Such a detector can preferably be embodied as one or more diodes. Alternative detectors can include pixelated detectors that provide more information during alignment, or scintillator-based detectors that can provide better sensitivity. Embodiments include detectors configured to detect X-ray radiation within a first energy range. The energy range can have an upper limit, a lower limit, or both. In an exemplary embodiment, a filter is arranged to block X-ray radiation with energy outside the first energy range from reaching the detector. Other embodiments can include detecting X-ray radiation from at least a first energy range and a second energy range, respectively. In particular, it can be advantageous to detect X-ray photons with energy within a desired energy range and X-ray photons with energy above the desired energy range, respectively. A first signal generated by photons within the desired energy range can be used during the alignment process. The alignment between the X-ray source and the X-ray optics and / or between the X-ray optics and the exit can be adjusted to increase this signal. A second signal generated by photons with energy above the desired energy range can be used to mitigate the fault, as described below.

[0009] Including a detector configured to detect X-ray radiation within a specific energy range directed toward the exit is advantageous because it can serve as an alignment tool, making adjustments to the position and / or orientation of the X-ray optics easier for the operator to perform or potentially automated. Furthermore, such a detector, together with a shutter placed at the exit, can also be used to block X-ray radiation with energies outside the desired energy range from being emitted through the exit. These and other advantages will be further described in the various exemplary embodiments described below.

[0010] Typically, X-ray systems are designed to deliver X-ray radiation within a predetermined photon energy range, and monochromatic X-ray optics are commonly used for this purpose. However, in the event of a malfunction, such as misalignment of components in the X-ray system, X-ray radiation with photon energies outside the predetermined range may pass through the optics. In some embodiments, this is addressed by configuring detectors to detect photons with energies outside the predetermined range (e.g., above the predetermined energy range). If the amount of photons with energies outside the predetermined energy range detected exceeds a predetermined threshold, the system can be configured to ensure the shutter is in a closed position to prevent any X-ray radiation of such energy from exiting through the outlet. Movement of the shutter between the closed and open positions is preferably achieved using electromechanical actuators, motors, etc.

[0011] X-ray systems may also include external radiation shielding or cabinets configured to block radiation. The cabinet may enclose at least some of the X-ray source, X-ray optics, sample location, and detection apparatus. For example, such an external cabinet may be configured to block radiation with photon energies corresponding to those of the X-ray optics designed to provide as output. In some embodiments, the detector may therefore be configured to detect radiation that may risk penetrating the external cabinet, while being insensitive to radiation corresponding to the intended output. In this way, X-ray radiation with energies higher than the predetermined energy range (which might otherwise be inadvertently emitted and potentially penetrate the external radiation shielding) can be detected and, upon detection, limited to the internal radiation shielding by ensuring the shutter is closed.

[0012] The detector provided for detecting X-ray radiation directed toward the exit can also be used for the alignment of components of the X-ray system. By detecting the X-ray radiation directed toward the exit (e.g., radiation within a predetermined range) and by feeding the detector signal from the detector to a controller, the alignment between the X-ray source and the X-ray optics and / or between the X-ray optics and the exit can be adjusted by the controller, thereby increasing the detector signal. For this purpose, the controller is preferably coupled to a manipulator that can be used to move the X-ray spot of the X-ray source and / or the position or orientation of the X-ray optics. Conveniently, this alignment can be performed when the shutter is in its closed position, thereby preventing any X-ray radiation from exiting through the exit. The manipulator arranged to adjust the position and / or orientation of the X-ray optics is therefore preferably controllable from outside the radiation-shielding housing. This is advantageous because poor alignment can cause X-ray radiation with energy outside the predetermined range to reach the exit.

[0013] The movement of an X-ray spot relative to an X-ray optics device can be achieved, for example, by moving the entire X-ray source, by deflecting an electron beam that strikes a target to generate X-ray radiation on the target, or by moving the X-ray target. Different translation modes can be used in different directions; for example, movement of the X-ray spot in a first direction can be achieved by deflecting the electron beam, while movement in another direction (e.g., perpendicular to the first direction) can be achieved by moving the target.

[0014] The movement of X-ray optical devices can be achieved, for example, by means of motors (such as stepper motors) or actuators (such as electromagnetic or piezoelectric actuators).

[0015] Several modifications and variations are possible within the scope of this invention. In particular, within the scope of the inventive concept, X-ray sources comprising multi-material targets, more than one target, or more than one electron beam are conceivable. X-ray optics designed to guide X-ray radiation of more than one well-defined wavelength are also conceivable. Furthermore, X-ray systems of the type described herein can be advantageously tailored to specific applications, such as, but not limited to, medical diagnostics, non-destructive testing, photolithography, crystal analysis, microscopy, materials science, microscopic surface physics, X-ray diffraction for protein structure determination, X-ray spectroscopy (XPS), critical-size small-angle X-ray scattering (CD-SAXS), and X-ray fluorescence spectroscopy (XRF). Attached Figure Description

[0016] In the following detailed embodiments, reference is made to the accompanying drawings, in which:

[0017] Figure 1 An example of an X-ray system is shown schematically;

[0018] Figure 2Another example of an X-ray system is illustrated schematically;

[0019] Figure 3 Another example of an X-ray system is illustrated schematically;

[0020] Figure 4 An exemplary detector arrangement is schematically shown;

[0021] Figure 5 A schematic flowchart of the method according to the present invention is shown. Detailed Implementation

[0022] Figure 1 An example of an X-ray system is schematically illustrated. The X-ray system has a housing 3 from which X-ray radiation is emitted through an X-ray transparent window 4. The X-ray radiation is generated by electrons emitted from an electron source 1 and striking a target 2 at an interaction region, thus generating an X-ray spot. A radiation-shielding housing 5 is arranged adjacent to the housing 3 and receives the X-ray radiation emitted through the window 4. X-ray optics 6 are disposed within the radiation-shielding housing 5. In this example, housing 5 and housing 3 are movable relative to each other. Therefore, alignment can be performed by moving housing 5 or housing 3, or both. To prevent radiation leakage, a radiation trap 9 can be arranged at the interface between housing 5 and housing 3. Housing 5 is provided with an outlet through which X-ray radiation can exit. To prevent unintentional X-ray radiation output, the outlet is provided with a shutter 7, which is movable between an open position that allows X-rays to exit through the outlet and a closed position that prevents X-rays from exiting through the outlet. When shutter 7 is closed, no X-ray radiation is emitted into the surrounding environment. When shutter 7 is open, X-ray radiation can be emitted through the outlet in the housing; otherwise, the outlet is covered by the shutter. One or more detectors can be provided, for example, on shutter 7 (in Figure 1 (Referring to 8 in the attached figure) to detect any X-ray radiation directed toward the exit. Therefore, when shutter 7 is closed, detector(s) 8 provide a signal indicating the amount of X-ray radiation reaching the shutter. During the alignment process, the relative positions of the X-ray optics and the X-ray spot can be adjusted to increase this signal.

[0023] It is also conceivable that the alignment process is performed based on feedback from a detector located at the sample location (i.e., where the sample to be studied is to be placed) or in the beam path upstream or downstream of the sample location. Shutter 7 is then in its open position during the alignment process so that X-ray radiation reaches the detector.

[0024] The X-ray optical element 6 can be a mirror, such as a multilayer mirror; a zone plate; a single capillary optical element; or a multicapillary optical element. In some preferred embodiments, the X-ray optical element is a Monte Carlo mirror. In other embodiments, the X-ray optical element can be implemented as a crystal optics device, such as a hyperboloid crystal optics device (DCC optics).

[0025] The interior of the radiation-shielding housing 5 can be under reduced pressure, or it can be filled with an inert gas such as helium or nitrogen. One reason for keeping the interior of housing 5 under reduced pressure or filling it with an inert gas is to reduce the accumulation of contaminants on the optical components 6 and / or to reduce the scattering and absorption of X-ray radiation.

[0026] Figure 2 Another illustrative embodiment is shown schematically. In this example, housing 5 is rigidly attached to housing 3. In this embodiment, alignment can be performed by adjusting the position of the X-ray spot on target 2 by moving the electron beam generated by electron source 1, or by adjusting the position or orientation of X-ray optics 6 by means of manipulator 10. Since housing 5 is rigidly and radiation-shieldedly attached to housing 3, no X-ray radiation will be emitted outside housing as long as shutter 7 is closed, regardless of the alignment process. In this embodiment, electron source 1 may include suitable electro-optic components, such as deflection plates or alignment coils, for adjusting the position of the X-ray spot on target 2. Manipulator 10 can provide manual or motorized movement of the X-ray optics. Preferably, manipulator 10, X-ray source 1, and detector 8 are connected to controller 11 for automatic alignment (shown by dashed lines in the figure), allowing for convenient alignment adjustments to increase detector signal. This embodiment can reduce the distance between optics 6 and the X-ray spot on target 2. X-ray source 1 is contained within housing 3, and therefore depressurization is not required within housing 5. Window 4 serves as an interface between the depressurization area within housing 3 and housing 5. Since housing 5 only needs to provide radiation shielding, the construction of manipulator 10 can be slightly simplified. Housing 5 can be flushed with an inert gas such as helium to reduce air scattering and absorption and also prevent contamination of X-ray optics.

[0027] Figure 3 Another illustrative embodiment is shown schematically. In this embodiment, the radiation-shielding housing 5 is extended to also include a housing for the X-ray source 1. The distance between the target 2 (and therefore the X-ray spot) and the X-ray optics 6 can then be further reduced, since an X-ray transparent window is not required between them. In this case, the decompression zone is located within the radiation-shielding housing 5. Therefore, the X-ray transparent window 4 is preferably located at the exit and is thus covered by the shutter when the shutter 7 is in its closed position. Figure 3This embodiment shown can be useful for X-ray systems designed to provide soft X-ray radiation (energy below about 4 keV). The X-ray source 1, the manipulator 10 for X-ray optics, and the detector(s) 8 can be coupled with… Figure 2 The implementation method is similar to that of the controller 11.

[0028] Figure 4 An exemplary detector arrangement is schematically illustrated. A plan view of the shutter 7 is shown, viewed along the X-ray beam path within the housing 5. The X-ray radiation emitted from the housing 5 passes through an exit... Figure 4 The image is schematically shown as a dashed circle. Two diodes 101 and 102 are positioned on the shutter 7, ahead of the exit when the shutter is closed. The first diode 101 is placed closest to the X-ray optics and is used to detect X-ray radiation within a predetermined desired energy range. The second diode 102 is positioned behind the first diode, viewed from the direction of the emitted X-ray radiation. Figure 4 In the diagram, a portion of the second diode 102 is shown in dashed lines to indicate its location behind the first diode 101. Therefore, the first diode can act as a high-pass filter for the second diode. The second diode can then be used to detect whether X-ray radiation with energies outside a predetermined energy range is emitted from the X-ray optics. If further energy filtering is required, an optional filter can be placed between the two diodes. Figure 4 (Not shown in the image).

[0029] Typically, embodiments may include one or more electromechanical actuators, motors, etc., for moving the shutter between its closed and open positions. Such actuators, motors, etc., may be connected to the controller discussed above or may have one or more separate dedicated controllers. In embodiments where the shutter position is controlled based on input from the detector, it is preferable to connect the detector and the actuator / motor to a common controller. The X-ray system can be implemented using a single controller that handles all control inputs and outputs.

[0030] refer to Figure 5An exemplary method of operating an X-ray system according to the invention includes generating an X-ray beam 501 using an electron-impacted X-ray source and guiding the X-ray beam 502 into a radiation-shielding housing having an X-ray exit. The X-ray beam is guided to the exit 503 using X-ray optics arranged within the radiation-shielding housing. A shutter 504 arranged at the exit is used to allow or block X-rays from exiting, wherein the shutter moves between an open position allowing X-rays to exit and a closed position blocking X-rays from exiting. The method may further include detecting 505 the X-ray radiation directed to the exit. Optionally, the method may include the further step of aligning 506 the relative orientation of the X-ray source spot and the X-ray optics to increase the amount of X-ray radiation emitted through the exit. This can be accomplished by adjusting the relative orientation when the shutter is closed, preferably using a controller simultaneously connected to one or more detectors and an alignment manipulator in the X-ray system. Adjustments can be performed such that the detected amount of X-ray radiation directed to the exit increases. The controller can be configured to stop further adjustments once the achieved increase falls below a limit value. In addition, the method may include a step of ensuring the shutter is closed by means of a controller when the detector detects X-ray radiation with energy outside a predetermined range.

[0031] In a further embodiment, the method includes adjusting the relative orientation between the 507 X-ray spot and the X-ray optics and / or between the X-ray optics and the exit, such that the amount of detected X-ray radiation with energy outside a predetermined range is below a predetermined threshold. Preferably, this adjustment is performed by a controller when the shutter is closed, thereby preventing X-ray radiation with energy outside the predetermined range from being emitted through the exit.

[0032] in conclusion

[0033] An X-ray system is disclosed, comprising: an electron-impact X-ray source configured to generate an X-ray beam; a radiation-shielding housing having an X-ray exit; an X-ray optical element disposed within the radiation-shielding housing, configured to direct the X-ray beam toward the exit; and a shutter disposed at the exit, movable between an open position allowing X-rays to exit through the exit and a closed position preventing X-rays from exiting through the exit. In some embodiments, X-ray radiation directed toward the exit is detected to facilitate alignment of components in the system and / or to prevent unintentional radiation output for safety reasons. A corresponding method for operating the X-ray system is also disclosed.

Claims

1. An X-ray system, comprising: Electron-impacted X-ray source, which is configured to generate an X-ray beam; A radiation-shielding enclosure having an X-ray outlet; An X-ray optical element disposed within the radiation-shielding housing is configured to direct the X-ray beam toward the outlet; as well as A shutter disposed at the exit is movable between an open position that allows X-rays to exit through the exit and a closed position that prevents X-rays from exiting through the exit. as well as A detector is disposed within the radiation-shielding housing and configured to detect X-ray radiation directed from the X-ray source toward the outlet; The detector is configured to detect X-ray radiation within a first energy range.

2. The system as claimed in claim 1, wherein, The detector includes a filter that prevents X-ray radiation with energy outside the first energy range from being detected.

3. The system as described in claim 1 or 2, wherein, The detector includes a diode.

4. The system as described in claim 1 or 2, wherein, The detector includes a first detector element for detecting X-ray radiation in the first energy range and a second detector element for detecting X-ray radiation in the second energy range.

5. The system as described in claim 1 or 2, wherein, The X-ray optical element is configured to transmit only X-ray photons within a predetermined energy range.

6. The system of claim 5, wherein, The first energy range is selected to fall outside the predetermined energy range.

7. The system of claim 5, wherein, The system is configured to ensure that the shutter is in the closed position when the detected photons with energy outside the predetermined energy range exceed a predetermined threshold.

8. The system of claim 1 or 2, further comprising a controller connected to receive a detector signal from the detector indicating X-ray radiation within a desired energy range, the controller being arranged to adjust the alignment between the X-ray source and the X-ray optics and / or between the X-ray optics and the outlet, such that the detector signal increases.

9. The system of claim 1 or 2, further comprising a manipulator controllable from outside the radiation-shielding housing, the manipulator being arranged to adjust the position and / or orientation of the X-ray optical element.

10. A method of operating an X-ray system, the method comprising: X-ray beams are generated by bombarding an X-ray source with electrons. The X-ray beam is guided into a radiation-shielded housing with an X-ray exit. The X-ray beam is directed to the outlet using X-ray optical elements arranged within the radiation-shielding housing; A shutter arranged at the outlet is used to allow or block X-rays from being output through the outlet by moving the shutter between an open position that allows X-rays to be output through the outlet and a closed position that blocks X-rays from being output through the outlet. as well as X-ray radiation within a first energy range directed toward the outlet is detected using a detector arranged within the radiation-shielding housing.

11. The method of claim 10, wherein, The X-ray optical element is configured to transmit X-ray radiation within a predetermined energy range.

12. The method of claim 11, wherein, The first energy range is selected to fall outside the predetermined energy range.

13. The method of claim 12, further comprising ensuring that the shutter is in the closed position when the detected photons having energy outside the predetermined energy range exceed the predetermined threshold.

14. The method of any one of claims 10 to 13, further comprising adjusting the alignment between the X-ray source and the X-ray optical element and / or between the X-ray optical element and the outlet, such that the detected X-ray radiation within a desired energy range directed toward the outlet increases.

15. The method of claim 13, further comprising adjusting the alignment between the X-ray source and the X-ray optical element and / or the alignment between the X-ray optical element and the outlet to reduce detected photons having energy outside the predetermined energy range to below the threshold.

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