Method and system for guided parameter selection in x-ray microscope

Abstract

An X-ray microscope system provides guided acquisition parameter selection. In particular, a computer receives a projection from a detector subsystem and generates a user interface to guide a user to select acquisition parameters of the projection.

Description

[0001] Related applications

[0002] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 487,064, filed on February 27, 2023, the entire contents of which are incorporated herein by reference. Background Art

[0003] X-ray analysis is a powerful imaging modality used to analyze internal structures at scales from millimeters to micrometers and nanometers. X-ray systems provide high-resolution images of samples, allowing their properties to be studied in detail. X-ray systems use an X-ray beam to illuminate the sample and then image the sample using a detector. The X-rays are then analyzed to generate an image or projection of the sample.

[0004] X-ray computed tomography (CT) is a non-destructive technique for converting projections from different angles into a three-dimensional (3D) volume of a sample. When the sample is scanned at different angles, a tomographic volume data set is reconstructed from a series of such projections via standard CT reconstruction algorithms. X-ray CT systems have many different configurations. In X-ray microscopy (XRM) and industrial CT systems, because the X-ray source and detector are large and the sample or object being scanned is typically small, the X-ray source and detector are largely fixed, while the sample rotates in the X-ray beam. For medical X-ray CT systems, the opposite is true, where the patient is stationary and the source / detector rotates around the patient.

[0005] Acquisition parameter selection is an essential part of operating an X-ray system. The X-ray source voltage and filter selection determine the X-ray beam's penetration and absorption of the sample, as well as the resolution of the sample's image. Camera exposure time and frame rate can be adjusted to optimize contrast, and the total number of projections can be adjusted to maximize information from the sample. Overall, parameter selection is crucial to ensuring the generated images are of the highest quality and achieve the user's goals.

[0006] Currently, users are given a protocol provided by the XRM system manufacturer to follow to manually facilitate parameter selection. Typically, the system provides the user with a series of guided guidelines to aid in selection. Summary of the Invention

[0007] The main challenge for users of X-ray systems, and specifically X-ray microscopes, is determining the acquisition parameters for a given XRM system, sample, and region of interest. Among other things, the user must consider which motion controller axis should be used to move the sample out for capturing the reference image, the X-ray source voltage, the X-ray source filtering, the camera exposure time, the number of frames, and the total number of projections. Each of these acquisition settings can affect image quality, and there is often a trade-off between throughput and image quality. Note that, for example, when using a flat panel detector, multiple frames are typically captured per exposure and averaged together before saving the image. The optimal number may be a function of pixel binning (binning).

[0008] The present invention involves using software to automatically guide and suggest acquisition parameters to the user.

[0009] In general, according to one aspect, the invention features an X-ray system, such as an XRM system, with guided and possibly automated acquisition parameter selection. The system includes an X-ray source subsystem for generating X-rays, a stage subsystem for holding, moving, and rotating a sample in the X-rays, a detector subsystem for detecting the X-rays after interacting with the sample, and a computer for receiving an image from the detector subsystem and generating acquisition parameters for the image.

[0010] Specifically, the system generally generates a user interface to guide the user to select image acquisition parameters.

[0011] Typically, a computer-generated user interface guides a user to capture one or more reference images and / or to capture one or more sample images.

[0012] Currently, images are captured at different X-ray source subsystem accelerating voltages and with different filters.

[0013] The computer analyzes one or more reference images without the sample in the field of view and (if captured) one or more sample images to generate suggested acquisition parameters. Preferably, the computer suggests several sets of acquisition parameters, providing different options with different tradeoffs between throughput and quality of the end result.

[0014] In general, according to another aspect, the invention features a method for guided acquisition parameter selection in an X-ray microscope system.

[0015] The method includes generating X-rays, detecting the X-rays after interacting with a sample, receiving an image via a computer, and generating a user interface to guide a user in selecting acquisition parameters for the image.

[0016] In general, according to another aspect, the invention features a user interface presented on a display of a microscope system, including controls for moving a source stage, a stage, and / or a detector stage, and a messaging area in which acquisition parameters are suggested.

[0017] The above and other features of the present invention (including various novel details of structure and combination of components) and other advantages will now be described in more detail with reference to the accompanying drawings and pointed out in the claims. It should be understood that the specific methods and devices embodying the present invention are shown by way of illustration and not limitation. The principles and features of the present invention may be used in various and numerous embodiments without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, reference numerals refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead being placed upon illustrating the principles of the invention. In the drawings:

[0019] Figure 1 is a schematic diagram of an X-ray microscope system to which the present invention is applied in one embodiment; and

[0020] Figure 2-Figure 6 Shown is a user interface generated by the microscope for guided acquisition parameter selection. DETAILED DESCRIPTION

[0021] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0022] The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In addition, the singular form and the articles "a", "an" and "the" are intended to include the plural form as well, unless expressly stated otherwise. It should also be understood that when the terms: include, contain, cover and / or encompass are used in this specification, they indicate the presence of the features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or combinations thereof. It should be further understood that when mentioning and / or showing an element (including a component or subsystem) connected or coupled to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should be further understood that terms (such as those defined in commonly used dictionaries, etc.) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly defined as such herein.

[0024] Figure 1 is a schematic diagram of an XRM system 200 to which the present invention may be applied.

[0025] The microscope system 200 shown is an X-ray CT system and generally includes several subsystems. An X-ray source subsystem 102 generates a polychromatic or possibly monochromatic X-ray beam 103. A stage subsystem 110 with an object holder 112 holds a sample or object 114 in the beam and positions and repositions it so that the sample 114 can be scanned in the stationary beams 103, 105. A detector subsystem 118 detects the beam 105 after it has been modulated by the sample. A base, such as a platform or optical table 107, provides a stable foundation for the microscope system 200 and its subsystems.

[0026] Generally speaking, stage subsystem 110 has the ability to position and rotate sample 114 within beam 103. Thus, stage subsystem 110 typically includes a linear stage and a rotational stage. The illustrated example features a precise three-axis stage 150 that translates and positions the sample along the x, y, and z axes very precisely, but within a relatively small range of travel. This allows the region of interest of object 114 to be located within beams 103 / 105. Three-axis stage 150 is mounted on a theta stage 152, which rotates sample 114 about the y-axis within the beam. Theta stage 152, in turn, is mounted on base 107.

[0027] In some embodiments, source subsystem 102 will typically be a synchrotron X-ray radiation source or alternatively a "laboratory X-ray source."

[0028] As used herein, "laboratory X-ray source" refers to any suitable source of X-rays, other than a synchrotron X-ray radiation source. Laboratory X-ray source 102 may be an X-ray tube in which electrons are accelerated in a vacuum by an electric field and injected into a metal target, emitting X-rays as the electrons decelerate in the metal. Typically, such a source generates a continuous spectrum of background X-rays that incorporates sharp peaks in intensity at certain energies derived from characteristic lines of the selected target, which depend on the type of metal target used.

[0029] In one example, the source subsystem 102 is a rotating anode (reflector) type or microfocus source with a tungsten target. Targets comprising molybdenum, gold, platinum, silver, or copper may also be used. Preferably, a transmission target configuration is used, in which the electron beam strikes a thin target from its back side. X-rays emitted from the other side of the target are used as the beam 103.

[0030] The x-ray beam generated by the source subsystem 102 is typically conditioned to suppress unwanted radiation energies or wavelengths. For example, energy filters (designed to select a desired x-ray energy range (bandwidth)) such as those held in the filter wheel 160 are used to eliminate or attenuate unwanted wavelengths present in the beam. These energy filters typically include an "air" filter, which corresponds to no filter, as well as a set of low-energy filters for filtering low-energy x-rays and a set of high-energy filters for filtering high-energy x-rays.

[0031] When object 114 is exposed to X-ray beam 103, X-ray photons or particles that propagate through sample 114 form a modulated beam 105 that is received by detector subsystem 118. In some other examples, an image is formed on detector subsystem 118 of microscope system 200 using an objective lens.

[0032] Typically, a magnified projected image of the object 114 is formed on the detector subsystem 118. The magnification of the x-ray table is equal to the inverse of the source-to-object distance 202 and the source-to-detector distance 204.

[0033] To achieve high resolution, embodiments of the X-ray CT system 200 further utilize a very high resolution detector 124-1 of the detector subsystem 118 and / or position the sample 114 close to the X-ray source system 102. In one implementation of the high resolution detector 124-1, a scintillator is used in conjunction with a microscope objective to provide additional optical magnification in the range of 2x to 100x or greater. The scintillator converts X-rays into an optical image that can be detected by a camera.

[0034] Other detectors are often included as part of the detector subsystem 118. For example, the detector subsystem 118 may include a low-resolution detector 124-2. In some examples, this may be a flat-panel detector and camera, or a detector with a low-magnification microscope objective. It is possible for the detector subsystem 118 to be configured with one, two, or more detectors 124.

[0035] Preferably, two or more detectors 124 - 1 , 124 - 2 are mounted on a turntable 122 of the detector subsystem 118 so that they can be alternately rotated into the path of the modulated light beam 105 from the sample 114 .

[0036] Typically, the source subsystem 102 and the detector subsystem 118 are mounted on respective z-axis stages. For example, in the illustrated example, the source subsystem 102 is mounted to the base 107 via a source stage 154, and the detector subsystem 118 is mounted to the base 107 via a detector stage 156. In practice, the source stage 154 and the detector stage 156 are relatively low-precision, high-travel range stages that allow the source subsystem 102 and the detector subsystem 118 to be moved, typically very close to the object during scanning, and then retracted to allow the object to be removed from the object holder 112 of the stage subsystem 110, a new object to be loaded onto the object holder 112 of the stage subsystem 110, and / or the object to be repositioned on the object holder 112 of the stage subsystem 110.

[0037] The operation of the microscope system 200 and the scanning of the object 114 are controlled by a computer subsystem 224 , which generally includes an image processor 220 and a controller 222 .

[0038] The computer system 224 includes one or more processors 260 and its data storage resources (such as disks or solid-state drives) and memory MEM. The processor 260 executes an operating system 262 and various applications running on the operating system 262 to allow a user to control and operate the microscope system 200. Specifically, a user interface application 250 executes on the operating system 262 and generates a user interface that is presented on a display device 236 connected to the computer subsystem 224. The user interface enables an operator to control the system and view projection images and tomographic reconstructions. User input devices 135, such as a touch screen, computer mouse, and / or keyboard, enable interaction between the operator and the computer subsystem 124. A parameter calculation application 252 receives user selections and reference image data and sample image data from the detector subsystem 118 via the user interface application 250 and determines possible parameter combinations that are forwarded back to the user via the user interface application 250.

[0039] The controller 222 allows the computer subsystem 224 to control and manage the components of the X-ray CT microscope 200 under software control. The controller can be a separate computer system suitable for handling real-time operations or an application program executed on the processor 260. The source subsystem 102 includes a control interface 130 that allows the controller 222 to control and monitor it. Similarly, the stage subsystem 110 and the detector subsystem 118 have corresponding control interfaces 132, 134 that allow the computer subsystem 224 to control and monitor them via the controller 222.

[0040] To configure the microscope system 200 to scan a sample and adjust other parameters (such as geometric magnification), the operator utilizes a user interface presented on the display device 236 and generated by the user interface application 250 to adjust the source-to-object distance 202 and the source-to-detector distance 204 through corresponding operation of the source stage 154 and the detector stage 156 to achieve the desired scanning settings.

[0041] Specifically, the source stage 154 and the detector stage 156 include respective motor encoder systems or other actuator systems that allow the computer system 224, via the controller 222, to position the respective X-ray source subsystem 102 and detector subsystem 118 to designated positions via the control interfaces 130, 134. Further, the source stage 154 and the detector stage 156 signal the controller 222 with respect to their actual positions.

[0042] Before performing a CT scan, an operator of the system operates the stage subsystem 110 via the computer subsystem, controller 222, and control interfaces 130, 132, 134. Typically, the stage subsystem 110 positions the object by controlling the theta stage 152 to rotate the object about an axis perpendicular to the optical axis of the x-ray beams 103, 105, and / or by using the stage 150 to position the sample in the x, y, and z directions.

[0043] Using a user interface presented on a display device 236 by a user interface application 250, an operator defines / selects a scan setup, including acquisition parameters, via a UI (user interface) device 235. These acquisition parameters include the X-ray source voltage and filter settings (which help determine the X-ray energy spectrum at the X-ray source subsystem 102), as well as the exposure time and number of frames per projection at the detector subsystem 118. The operator typically also selects other settings, such as the field of view (FOV) of the X-ray beam 103 incident on the sample 114, the number of X-ray projection images to be created for the sample 114, and the selected detectors 124-1 and 124-2. Typically, acquisition parameters include the X-ray source voltage, X-ray source filtering, camera exposure time, number of frames per projection, and the total number of projections, and the scan setup includes the angle and position of rotation of the stage subsystem 110 relative to the sample. In addition, a source-to-object distance 202 and a source-to-detector distance 204 are typically specified, and these are converted into the necessary positions or settings of the source stage 154 and detector stage 156 and / or the sample stage as part of the scan setup. The parameter calculation application 252 determines different combinations of these parameters to facilitate user operation of the system 200 .

[0044] The microscope system 200 includes an optical camera 210, such as a video camera, that collects image data of a sample 114 held in an object holder 112. The camera is typically mounted directly or indirectly to the system base 107 via a mounting system 215, such as a holder. Typically, the optical camera 210 collects images in the visible portion of the spectrum and / or in adjacent spectral regions, such as infrared. Typically, the optical camera 210 includes a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensor. A light source 212 is also included to illuminate the object in the spectral region used by the optical camera.

[0045] operate:

[0046] Figure 2 A user interface 500 is shown generated by a user interface application 250 executing on an operating system 262 of a computer system 224 and presented on a display device 236 .

[0047] The user interface 500 includes a projection pane 310. This presents a projection or image captured by the detector subsystem 118.

[0048] The continuous image button 312 , the single image button 314 , and the reference image button 316 enable a user to capture corresponding images from the XRM system 200 .

[0049] The user interface 500 includes the optical camera pane 318 , which shows current image data received from the optical camera 210 .

[0050] The message pane 350 provides guidance to the user and receives user instructions for configuring the system 200 .

[0051] The motion controls are located at the bottom of the window. The sample x position control area 330 enables movement of the sample or object 114 along the x-axis by controlling the three-axis stage 150 to move the object holder 112, the sample y position control area 332 enables movement along the y-axis by controlling the three-axis stage 150, the sample z position control area 334 enables movement along the z-axis by controlling the three-axis stage 150, the sample theta control area 336 enables rotation of the object holder 112 by controlling the theta stage 152 to rotate the sample or object 114, the source position control area 338 enables z-axis movement of the source by controlling the source stage 154, and the detector position control area 340 enables z-axis movement of the detector subsystem 118 by controlling the detector stage 156.

[0052] like Figure 2As shown, the user interface application 250 initially presents options for how the parameter calculation application 252 may acquire the reference image via a message pane 350. A radio button group 352 allows selection between automatic referencing, sample too large, or guided methods.

[0053] Automatic reference selection will move the sample according to the selected reference axis. This example shows the Y axis selection, but the X or Z axis can be selected alternatively. This causes the three-axis stage 150 to move the sample out of the field of view to obtain a reference image by moving the corresponding axis.

[0054] It also provides the situation that the sample is too large to obtain a reference image. This occurs when the sample cannot be completely moved out of the field of view. In this case, the system will prompt the user to remove the sample 114 via the message pane.

[0055] Finally, the user interface application 250 of the system 200 provides a step-by-step guided procedure by selecting the third radio button. In this procedure, to determine the axis for moving the sample out to obtain a reference image, the software is designed to test different reference axes in sequence and prompt the user after each test to confirm whether the current axis is sufficient.

[0056] In some implementations, the axis is determined without user prompting from automatic analysis of the image or from a CAD model of the system and sample.

[0057] Next, Figure 3 As shown, the user interface application 250 guides the user through the message pane 350 to define one or more target regions of interest for the sample. In this procedure, the user is instructed to define a box in the projection pane 310 that will be used to calculate and determine appropriate acquisition parameters. Specifically, the area should be generally uniform, or all features within it should have equal importance. In addition, the selected area should not contain any air.

[0058] To facilitate this process, the projection pane 310 is provided with a region of interest overlay 354. Specifically, the user uses the user interface device 235 (e.g., a computer mouse) to adjust the size of the region of interest overlay 354 so that it covers the desired target area relative to the projection being displayed in the projection pane 310. The designated region of interest will be used by the parameter calculation application 252 to determine acquisition parameters.

[0059] Figure 4 The interface is shown and in particular the message pane 350. Here it outlines a series of steps in which images are taken to help determine the optimal parameters.

[0060] First, the sample is moved to the recipe point position and the "air" filter is applied.

[0061] An image or projection of the sample is then captured using an air filter with the X-ray source set to 80 kV, followed by a reference image captured at the same settings. Next, the source filter LE1 is applied by controlling the filter wheel 160 .

[0062] Next, a reference image and a sample image are captured at 80 kV, followed by a reference image and a sample image at 60 kV, and then a reference image and a sample image at 40 kV.

[0063] Finally, if the user chooses to take a final image for recommendation, a 50 kV reference image is also captured. These different images are automatically captured by the system 200 and the images are passed to the parameter calculation application 252.

[0064] In practice, the decision tree changes significantly after the first 80 kV air image. For example, if the reference image is too large and the reference method is selected, the system next takes a 140 kV air image, then asks the user to remove the sample from the system, and then takes reference images at both 80 kV and 140 kV. More typically, the second image is the 80 kV air reference image. The decision tree implemented by the system indicates whether it already has enough information to select a filter, or whether it needs to first take both the sample image and the reference image at 140 kV. After selecting the filter, the system dynamically chooses what to do next based on the information it has up to that point.

[0065] Figure 5 A message pane 350 is shown that provides one or more different parameter settings 358A, 358B, 358C determined by the parameter calculation application 252. The first 358A will produce the best quality image scan, the last 358C will produce the fastest scan, and the intermediate parameter list 358B provides an efficient scan that will optimize both image quality and speed.

[0066] This series of images can be driven by different decision trees, models, simulations, or machine learning.

[0067] More generally, filter selection was based on transmittance in the initial 80 / 140 kV images taken with the "air" filter.

[0068] For kV, a range of 20%-35% transmission is desirable. However, it should be noted that there are many cases, like the one in the example, where the transmission range cannot be achieved with the selected filters, so the figure shows the closest the system can get to this range.

[0069] In the current example, the exposure time recommendation is based on a calculated amount of time that brings the median count in the sample image ROI (region of interest, the area defined by stack 354) to 5000. In other approaches, a better trade-off between the number of counts and the number of projections can be provided. In any case, with the current implementation, there are many situations where, for example, 5000 counts is not optimal / possible due to the boundary conditions defined for the exposure time (minimum limit based on camera capabilities, minimum limit to avoid shutter artifacts / minimum limit to avoid inefficient scanning due to overhead time between projections, upper limit to avoid saturation, and upper limit to maintain a total scan time of 90s). Sometimes these limits conflict with each other, so the priority of these boundary conditions also needs to be determined.

[0070] Once the user selects the desired parameter settings, scanning begins, such as Figure 6 Status window 390 is shown.

[0071] While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as encompassed by the appended claims.

Claims

1. An X-ray system, such as an X-ray microscope system, having guided acquisition parameter selection for acquiring computed tomography (CT) scans, comprising: An X-ray source subsystem for generating X-rays; a stage subsystem for holding a sample in the X-rays; a detector subsystem for capturing sample and reference images; as well as A computer is configured to receive images from the detector subsystem and generate suggested acquisition parameters for a scan.

2. The system according to claim 1, wherein: The computer-generated user interface guides a user in selecting a method for capturing one or more reference images and guides the user in selecting the suggested acquisition parameters.

3. The system according to any one of claims 1 to 2, wherein: The user interface generated by the computer guides the user to capture one or more sample images of the sample.

4. The system according to any one of claims 1 to 3, wherein: The user interface generated by the computer includes a user-adjustable ROI overlay on the captured sample image.

5. The system according to any one of claims 1 to 4, wherein: The sample image and the reference image are captured under different X-ray source subsystem accelerating voltages, different filters, and different exposure times.

6. The system according to any one of claims 1 to 5, wherein: The computer analyzes the one or more reference images and the one or more sample images to generate the suggested acquisition parameters.

7. The system according to any one of claims 1 to 6, wherein: The computer suggests several acquisition parameters.

8. A method for guided acquisition parameter selection in an X-ray system, such as an X-ray microscope system, comprising: Generate X-rays; detecting the X-rays after interacting with the sample; as well as receiving images via a computer; as well as The user is guided through the analysis of the image to find the acquisition parameters.

9. The method according to claim 8, wherein The computer-generated user interface guides the user in selecting a method for capturing one or more reference images and guides the user in selecting the suggested acquisition parameters.

10. The method according to claim 9, wherein: The user interface generated by the computer guides the user to capture one or more sample images of the sample.

11. The method according to any one of claims 9 to 10, wherein The user interface generated by the computer includes a user-adjustable ROI overlay on the captured sample image.

12. The method according to any one of claims 9 to 11, wherein The sample image and the reference image are captured under different X-ray source subsystem accelerating voltages, different filters, and different exposure times.

13. The method according to any one of claims 9 to 12, wherein The computer analyzes the one or more reference images and the one or more sample images to generate the suggested acquisition parameters.

14. A user interface presented on a display of a microscope system, comprising: a control for moving the source stage and / or the object stage and / or the detector stage; as well as A message sending area, in which collection parameters are suggested.

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