Abstract
Synchrotron radiation micro-computed tomography (SR-µCT) is a vital technique for the quantitative characterization of three-dimensional internal structures across diverse fields, including energy, integrated circuits, materials science, biomedicine, archaeology etc. While SR-µCT provides high spatial resolution and high image contrast, it typically offers only moderate temporal resolution, with acquisition times ranging from minutes to hours. Recently, dynamic SR-µCT has attracted significant interest for its capacity to capture real-time three-dimensional structural evolution. Here, we demonstrate a dynamic SR-µCT system operating at 26.7
Introduction
X-ray micro-computed tomography (µCT) is a non-destructive inspection technique widely used to visualize sample morphology and evaluate quantitative information on three-dimensional (3D) geometry and properties.1,2 Since the advent of third-generation synchrotron radiation (SR) facilities in the 1990s, SR-µCT has gained prominence due to its superior advantages, including a large field of view (FOV), high spatial resolution, and high contrast. This high contrast is largely attributable to phase-contrast imaging, which offers exceptional sensitivity, particularly for low-Z materials such as those found in biomedical and carbon-based samples.
Consequently, SR-µCT has evolved into a widely utilized technique for the quantitative characterization of 3D internal structures across diverse research fields, including integrated circuits, energy, materials, and environmental science. 3 Representative applications include imaging of a variety of electrode components before, during, and after battery operation, 4 investigating an entire 3D stacked chip package at high resolutions in minutes, 5 studying ancient and historical materials, 6 investigating the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. 7 These cases demonstrate that SR-µCT is a powerful technique capable of providing high-resolution and high-contrast 3D images. However, its main limitation has traditionally been a moderate temporal resolution, typically ranging from several minutes to hours per scan.
In recent years, monochromatic-beam-based dynamic SR-µCT with a FOV on the millimeter-to-centimeter scale has attracted increasing attention and has been applied across numerous research fields.8,9 Applications include analyzing imaging the time evolution of the pore and micro-fracture networks during oil shale pyrolysis, 10 studying the fragmentation and growth dynamics of dendritic microstructures, 11 unraveling dynamic processes in geologic systems, 12 studying the tissue motion for regional lung function, 13 and investigating the dynamics of enhanced gas trapping applied to CO2 storage in the presence of oil. 14 The high energy resolution of the synchrotron monochromatic beam enables this technique to provide quantitative information. 15 However, a fundamental trade-off exists between temporal resolution and FOV. Using a bending magnet or wiggler source can provide a centimeter-scale FOV, but the resulting temporal resolution is only moderate due to low flux density. Conversely, an undulator source delivers high flux density suitable for high temporal resolution, but the usable beam size is typically restricted to a few millimeters. Consequently, achieving high spatiotemporal resolution with a monochromatic beam and a large FOV (e.g., centimeters) remains highly challenging. To realize high spatiotemporal SR-µCT with a large FOV, the white beam from a bending magnet or wiggler source is often employed. This approach leverages the significantly higher flux compared to a monochromatic beam, enabling faster data acquisition across a larger FOV. 16
Here, we present the development of a filtered white beam-based dynamic SR-µCT system operating at 26.7
Materials and methods
Beamline
The dynamic SR-µCT experiment was conducted at the BL09B test beamline at SSRF. The test beamline was designed for at-wavelength metrology to evaluate the performance of beamline optical components and experimental instrumentation.
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As illustrated in Figure 1, the beamline employs a 1.27

Schematic of the BL09B test beamline.
During the white-beam dynamic SR-µCT experiment, all beamline optical components at BL09B were switched out, allowing the X-ray beam to pass solely through the beryllium (Be) window located approximately 38 meters from the source. The white-beam spectrum after the Be window is shown in Figure 2 (solid blue line), exhibiting a peak energy around 7

The spectrum of the BL09B test beamline at the SSRF.
Experimental setup
Figure 3 shows the experimental setup for dynamic SR-µCT installed in the experimental hutch at BL09B of SSRF. The system consists of several key components: an in-house-developed air-cooled millisecond fast shutter capable of providing a minimum beam window of 30 milliseconds; a white-beam filter system; an air-bearing rotation stage (Aerotech) with a maximum rotation speed of 4800°/s; a high-speed X-ray detector; and a clock synchronization system to coordinate all instruments.

The experimental step up of white beam dynamic SR-µCT (a), the Aerotech stage and alignment stages (b), and the L-type optics-coupled detector (c).
The white beam, generated by the 1.27

The air-cooling white beam shutter.
The 1

The accuracy (left) and tilt error (right) test results of the air-bearing rotation stage.
The detector features an L-shaped optics-coupled system, as depicted in Figure 6 and summarized in Table 1. The optical coupling system employs a long-working-distance microscope objective arranged in an L-shaped configuration, with the objective positioned behind a reflecting mirror. This design keeps the microscope objective out of the direct X-ray path, thereby shielding it from radiation damage caused by direct exposure. The optical system is optimally designed to accommodate a large numerical aperture (NA) microscope objective, significantly enhancing light collection efficiency. Additionally, the scintillator thickness is carefully matched to the NA of the microscope objective to achieve optimal imaging resolution and contrast.

The sketch of the L-type optics-coupled detector.
The parameters of optics-coupled detector.
The detector consists of a 50
It is crucial to synchronize all instruments in white-beam dynamic SR-µCT to carefully protect the sample and detector from excessive heat load. Figure 7 illustrates the control system and timing chart designed for this purpose. A central PC initiates the experiment by sending a start signal to a Stanford Research Systems DG535 digital delay/pulse generator and subsequently receives the acquired data from the Photron FASTCAM SA-Z camera upon completion. The DG535 unit serves as the master clock synchronizer, coordinating the actions of the photon shutter, white-beam shutter, air-bearing rotation stage, and high-speed camera. Specifically, upon receiving the start signal from the PC (t = 0

The control system (a) and timing chart (b) of dynamic SR-µCT.
Samples and data collection
Three samples were scanned using the dynamic SR-µCT system. The first sample consisted of polymethyl methacrylate (PMMA) spheres with diameters ranging from 50 μm to 200 μm, tightly packed in a plastic tube. This static sample was used to evaluate the capability and stability of the system under two distinct scanning modes: dynamic continuous rotation and conventional step-and-snap acquisition. In the dynamic continuous rotation mode, the rotation stage rotated continuously while the detector acquired projection images without synchronization between the two devices. In the step-snap mode, the stage rotated to each prescribed angle and paused, after which a trigger signal was sent to open the shutter and acquire a projection image. Upon receiving a completion signal from the detector, the shutter closed and the stage advanced to the next angle. This iterative process continued until the full angular range was covered. The inter-device communication and mechanical motion in step-snap mode resulted in a total acquisition time of approximately 600
The second sample was a fully dried Pittosporum tobira stem, selected for its complex microarchitecture and structural stability during the brief scan time of approximately 0.36
All samples were mounted at the center of the rotation stage using 3
The experimental parameters of two samples.
The sample-to-detector distance was set to 33.5
Data processing
Data processing and 3D rendering for dynamic SR-µCT present substantial challenges due to the large data volumes involved—a single experiment can generate hundreds of gigabytes comprising hundreds or even thousands of individual CT scans. Manual processing and visualization of such datasets would be prohibitively time-consuming, underscoring the need for automated or semi-automated computational workflows.
In this study, dynamic SR-µCT data were processed using PITRE software, 20 a comprehensive and freely available software for synchrotron-based CT data. To meet the demands of dynamic imaging, PITRE incorporates an optimized processing pipeline: once key reconstruction parameters are manually defined, the software automatically generates and executes a batch processing task for the entire dynamic dataset. For instance, with a single command, PITRE can initiate reconstruction of all time-resolved CT volumes, specifying the number of projections per reconstruction and the interval between successive scans.
For the PMMA spheres and dried Pittosporum tobira stem, slices were reconstructed without phase retrieval to preserve edge-enhancement effects, which aid in visualizing fine structural details and identifying potential artifacts. In contrast, for the live ant sample, the phase-attenuation duality Paganin algorithm was applied to all projections prior to reconstruction. 21 This approach yielded slices in which materials with higher refractive indices appeared brighter and those with lower indices darker. All reconstructions were performed using the filtered back-projection algorithm with a Shepp–Logan filter. The parameters of dynamic SR-µCT data processing are summarized in Table 3.
The parameters of dynamic SR-CT data processing.
3D rendering of the live ant dataset was carried out semi-automatically using Dragonfly software. 22 Dragonfly supports Python scripting and allows the development of custom add-ons to implement specific workflows. Users can either execute commands directly in the integrated Python console or record a sequence of operations into a macro for automating repetitive tasks. This macro functionality was leveraged to achieve efficient, semi-automated 3D visualization of the time-resolved volumetric data.
Results
Reconstructed slices of the PMMA sphere sample obtained using both dynamic CT mode and step-snap mode are presented in Figure 8. The slice acquired in dynamic CT mode exhibits slightly more pronounced stripe artifacts, particularly in the region highlighted in orange, which can be attributed to the relatively limited number of projection images acquired in this mode. In addition, a slight blurring effect is visible in the dynamic CT results, arising from the continuous rotation of the sample during exposure, which leads to angular integration within each projection.

Reconstructed slices of PMMA spheres sample with dynamic CT mode (a) and step-snap mode (b), (c) the differential image between (a) and (b), (d) and (e) the enlarged views of (a) and (b) respectively.
Despite these minor artifacts, the overall structural features of the PMMA spheres and the plastic tube remain clearly identifiable in the dynamic CT mode and are consistent with those obtained in the step-snap mode. The total hard X-ray exposure times were 0.36
Artifacts such as blurring—especially in spheres located farther from the center of rotation—can arise from several experimental factors, including inadequate sample fixation, centrifugal forces-induced motion, instability in rotation or camera acquisition speed, or incorrect projection number settings during reconstruction. Although it can be challenging to pinpoint the exact cause when such artifacts occur, the close agreement between the dynamic and step-snap reconstructions in this study confirms the stability and reliability of the dynamic CT system under the employed conditions.
A reconstructed slice, line profile, and enlarged views of the Pittosporum tobira stem are presented in Figure 9. The images reveal fine structural details with high clarity, capturing vascular tissues of varying dimensions. The line profile demonstrates sharp contrast transitions between different material, confirming excellent differentiation capability. Both the PMMA spheres and Pittosporum tobira stem were reconstructed using 940 projections, a value consistent with theoretical calculations based on the rotation stage speed and detector frame rate. The quality of these reconstructions demonstrates the robust performance of the dynamic SR-µCT system.

A reconstructed result of pittosporum tobira stem sample: (a) slice, (b) the profile of green line in (a), (c) and (d) the enlarged areas images in (a).
Figure 10 presents reconstructed cross-sections along the reference yellow line (indicated in the 0

Reconstructed slice at the yellow line position in the 0

3D rendering images of a live ant at different times with Dragonfly software.
Figure 11 shows 3D renderings of the live ant at corresponding time points, processed using Dragonfly software. While the ant's torso remained relatively stable due to confinement in the plastic container, significant leg movement is evident (yellow arrows). Despite these rapid motions, the reconstructed images maintain clear, smooth contours throughout the appendages, demonstrating that the system's 25
Discussions
The dynamic SR-µCT has garnered significant interest due to its ability to capture three-dimensional structural evolution across diverse fields such as biomedicine, materials science, energy research, and semiconductor technology. A key advantage of SR-µCT lies in its high spatial and contrast resolution, yet there remains a growing need to image larger, centimeter-scale samples typical in these applications. Thus, an ideal dynamic SR-µCT system should combine high spatial, temporal, and contrast resolution with a sufficiently large FOV.
This is often achieved using white beam sources from bending magnets or wigglers at synchrotron facilities, which can readily provide centimeter-scale beam sizes at dedicated imaging beamlines. Notably, wiggler sources offer a flux density one to two orders of magnitude higher than bending magnets, enabling substantially improved temporal resolution in dynamic imaging. However, the increased heat load associated with wigglers must be carefully managed, for instance, through the use of water-cooled shutters.
When an undulator source is employed at a dedicated imaging beamline, the flux density can be several orders of magnitude higher than that of wigglers, though the available beam size is considerably smaller—typically around 2
In the current study, a temporal resolution of 26.7
Data processing for dynamic SR-µCT remains a considerable challenge due to the immense data volumes, which can reach terabytes per day. GPU-accelerated parallel computing on cluster systems is an effective strategy to enhance processing speed. 24 While many synchrotron facilities have established such computational clusters to handle these resource-intensive tasks, potential bottlenecks may include data transfer rates between PCs or clusters, as well as data read/write speeds between memory and hard disks. Addressing these limitations will be essential to fully leverage the capabilities of high-speed dynamic SR-µCT.
Conclusions
A dynamic SR-µCT system operating at 26.7
Footnotes
Acknowledgments
The dynamic CT instruments were preliminary tested at BL13W1 at the SSRF.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was funded by the National Key R&D Program of China (2022YFA1604002), the Guangdong Special Support Program (2023TQ07Z464), the National Natural Science Foundation of China (12405366), the Shenzhen Science and Technology Program (JCYJ20250527151304001).
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
