Quality and parameter control of X-ray absorption gratings by angular X-ray transmission

Gustschin, Nikolai; Gustschin, Alex; Meyer, Pascal; Viermetz, Manuel; Riederer, P.; Herzen, Julia; Mohr, Jürgen; Pfeiffer, Franz

doi:10.1364/oe.27.015943

Cited by 13 publications

(16 citation statements)

References 22 publications

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“…Ensuring the uniformity of the gratings’ duty cycle and lamella height is crucial for maximising the visibility of the setup and, thus, image quality. The newly developed angular X-ray transmission 28 (Fig. 2f ) allows for non-destructive and easily implementable parameter examination of gratings, and conventional SEM (Fig.…”

Section: Resultsmentioning

confidence: 99%

Dark-field chest X-ray imaging for the assessment of COVID-19-pneumonia

et al. 2022

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Background Currently, alternative medical imaging methods for the assessment of pulmonary involvement in patients infected with COVID-19 are sought that combine a higher sensitivity than conventional (attenuation-based) chest radiography with a lower radiation dose than CT imaging. Methods Sixty patients with COVID-19-associated lung changes in a CT scan and 40 subjects without pathologic lung changes visible in the CT scan were included (in total, 100, 59 male, mean age 58 ± 14 years). All patients gave written informed consent. We employed a clinical setup for grating-based dark-field chest radiography, obtaining both a dark-field and a conventional attenuation image in one image acquisition. Attenuation images alone, dark-field images alone, and both displayed simultaneously were assessed for the presence of COVID-19-associated lung changes on a scale from 1 to 6 (1 = surely not, 6 = surely) by four blinded radiologists. Statistical analysis was performed by evaluation of the area under the receiver–operator-characteristics curves (AUC) using Obuchowski’s method with a 0.05 level of significance. Results We show that dark-field imaging has a higher sensitivity for COVID-19-pneumonia than attenuation-based imaging and that the combination of both is superior to one imaging modality alone. Furthermore, a quantitative image analysis shows a significant reduction of dark-field signals for COVID-19-patients. Conclusions Dark-field imaging complements and improves conventional radiography for the visualisation and detection of COVID-19-pneumonia.

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Section: Resultsmentioning

confidence: 99%

Dark-field chest X-ray imaging for the assessment of COVID-19-pneumonia

et al. 2022

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“…Grating Characterization. The AXT analysis method used for grating characterization provides spatially resolved mapping of several grating parameters and was originally proposed for rectangular, high-aspect ratio absorption gratings (36). However, it is also applicable to our phase grating G 1 considering two aspects.…”

Section: Methodsmentioning

confidence: 99%

“…2 A , an example of a 280-µ m-high grating structure with an aspect ratio exceeding 100 demonstrates the most recent LIGA fabrication results. In order to closely monitor and improve the fabrication process at this level and to ensure coverage of the whole detector surface with sufficient grating quality and low defect rate, we have developed a dedicated angular X-ray transmission (AXT) analysis, which extends the standard quality control process ( 36 ). For that purpose, we assign a quality shape factor to characterize the fabricated gratings.…”

Section: Optimization and Characterization Proceduresmentioning

confidence: 99%

Dark-field computed tomography reaches the human scale

Viermetz

Gustschin

Schmid

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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X-ray computed tomography (CT) is one of the most commonly used three-dimensional medical imaging modalities today. It has been refined over several decades, with the most recent innovations including dual-energy and spectral photon-counting technologies. Nevertheless, it has been discovered that wave-optical contrast mechanisms—beyond the presently used X-ray attenuation—offer the potential of complementary information, particularly on otherwise unresolved tissue microstructure. One such approach is dark-field imaging, which has recently been introduced and already demonstrated significantly improved radiological benefit in small-animal models, especially for lung diseases. Until now, however, dark-field CT could not yet be translated to the human scale and has been restricted to benchtop and small-animal systems, with scan durations of several minutes or more. This is mainly because the adaption and upscaling to the mechanical complexity, speed, and size of a human CT scanner so far remained an unsolved challenge. Here, we now report the successful integration of a Talbot–Lau interferometer into a clinical CT gantry and present dark-field CT results of a human-sized anthropomorphic body phantom, reconstructed from a single rotation scan performed in 1 s. Moreover, we present our key hardware and software solutions to the previously unsolved roadblocks, which so far have kept dark-field CT from being translated from the optical bench into a rapidly rotating CT gantry, with all its associated challenges like vibrations, continuous rotation, and large field of view. This development enables clinical dark-field CT studies with human patients in the near future.

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“…Ensuring the uniformity of the gratings' duty cycle and lamella height are crucial for maximizing the visibility of the setup and thus image quality. The newly developed angular X-ray transmission 19 (Figure 1f) allows for non-destructive and easily implementable parameter examination of gratings, and conventional SEM (Figure 1f, Inlet) was used for local and surface-based analysis. The interferometric visibility also depends on the number of moiré fringes as depicted in Figure 1g.…”

Section: The Dark-field X-ray Prototypementioning

confidence: 99%

“…The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a global medical, social, and economic crisis. The respective respiratory illness, coronavirus disease 2019 (COVID- 19), has so far caused over six million deaths worldwide 4 . At present, the reverse transcription-polymerase chain reaction (RT-PCR) test is the standard of reference for the definitive diagnosis of COVID-19 5,6 .…”

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confidence: 99%

Dark-field Chest X-ray Imaging for the Assessment of COVID‑19‑Pneumonia

Frank

Gassert

Urban

et al. 2022

Preprint

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Medical imaging is performed in daily clinical routine for the assessment of pulmonary involvement in patients infected with COVID-19. As conventional (attenuation-based) chest radiography provides only a low sensitivity for COVID-19-pneumonia, CT is the gold standard for lung imaging in COVID-19 patients. However, CT imaging exposes the patient to a considerable amount of radiation, and is not as widely available as plain chest X-rays. Therefore, alternative low-dose imaging X-ray techniques are highly desirable. Here we present the first clinical results employing a novel dark-field chest X-ray imaging method for the assessment of COVID-19-pneumonia. The work is based on recent technological advancements in a human-scale X-ray dark-field chest imaging prototype that enable the acquisition of quantitative dark-field radiographs with diagnostic image quality at a radiation dose comparable to conventional X-rays. In a reader study, we found that dark-field imaging has a higher sensitivity for COVID-19-pneumonia than attenuation-based imaging, and that the combination of both is superior to one imaging modality alone. Furthermore, a quantitative image analysis showed a significant reduction of signal in X-ray dark-field chest radiographs of COVID-19 patients. While our results demonstrate that dark-field chest radiography presents an ultra-low-dose alternative to CT imaging for the assessment of COVID-19-pneumonia, we anticipate that the presented technique will also be useful for therapy follow-up of patients with long-COVID-syndrome and, more generally, for the imaging of other pulmonary pathologies.

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Quality and parameter control of X-ray absorption gratings by angular X-ray transmission

Cited by 13 publications

References 22 publications

Dark-field chest X-ray imaging for the assessment of COVID-19-pneumonia

Dark-field chest X-ray imaging for the assessment of COVID-19-pneumonia

Dark-field computed tomography reaches the human scale

Dark-field Chest X-ray Imaging for the Assessment of COVID‑19‑Pneumonia

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