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De Marco F, Andrejewski J, Urban T, Willer K, Gromann L, Koehler T, Maack HI, Herzen J, Pfeiffer F. X-Ray Dark-Field Signal Reduction Due to Hardening of the Visibility Spectrum. IEEE TRANSACTIONS ON MEDICAL IMAGING 2024; 43:1422-1433. [PMID: 38032773 DOI: 10.1109/tmi.2023.3337994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
X-ray dark-field imaging enables a spatially-resolved visualization of ultra-small-angle X-ray scattering. Using phantom measurements, we demonstrate that a material's effective dark-field signal may be reduced by modification of the visibility spectrum by other dark-field-active objects in the beam. This is the dark-field equivalent of conventional beam-hardening, and is distinct from related, known effects, where the dark-field signal is modified by attenuation or phase shifts. We present a theoretical model for this group of effects and verify it by comparison to the measurements. These findings have significant implications for the interpretation of dark-field signal strength in polychromatic measurements.
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Tao S, Tian Z, Bai L, Wang W, Xu Y, Kuang C, Liu X. Tri-directional x-ray phase contrast multimodal imaging using one hexagonal mesh modulator. Phys Med Biol 2023; 68:195017. [PMID: 37652041 DOI: 10.1088/1361-6560/acf5c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 08/31/2023] [Indexed: 09/02/2023]
Abstract
Objective. X-ray phase contrast imaging is a promising technique for future clinical diagnostic as it can provide enhanced contrast in soft tissues compared to traditional x-ray attenuation-contrast imaging. However, the strict requirements on the x-ray coherence and the precise alignment of optical elements limit its applications towards clinical use. To solve this problem, mesh-based x-ray phase contrast imaging method with one hexagonal mesh is proposed for easy alignment and better image visualization.Approach. The mesh produces structured illuminations and the detector captures its distortions to reconstruct the absorption, differential phase contrast (DPC) and dark-field (DF) images of the sample. In this work, we fabricated a hexagonal mesh to simultaneously retrieve DPC and DF signals in three different directions with single shot. A phase retrieval algorithm to obtain artifacts-free phase from DPC images with three different directions is put forward and false color dark-field image is also reconstructed with tri-directional images. Mesh-shifting method based on this hexagonal mesh modulator is also proposed to reconstruct images with better image quality at the expense of increased dose.Main results. In numerical simulations, the proposed hexagonal mesh outperforms the traditional square mesh in image evaluation metrics performance and false color visualization with the same radiation dose. The experimental results demonstrate its feasiblity in real imaging systems and its advantages in quantitive imaging and better visualization. The proposed hexagonal mesh is easy to fabricate and can be successfully applied to x-ray source with it spot size up to 300μm.Significance. This work opens new possibilities for quantitative x-ray non-destructive imaging and may also be instructive for research fields such as x-ray structured illumination microscopy (SIM), x-ray spectral imaging and x-ray phase contrast and dark-field computed tomography (CT).
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Affiliation(s)
- Siwei Tao
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Zonghan Tian
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Ling Bai
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Wei Wang
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yueshu Xu
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
- State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 315100, People's Republic of China
| | - Cuifang Kuang
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
- State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 315100, People's Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Xu Liu
- State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
- State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 315100, People's Republic of China
- Ningbo Research Institute, Zhejiang University, Ningbo 315100, People's Republic of China
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Taphorn K, Kaster L, Sellerer T, Hötger A, Herzen J. Spectral X-ray dark-field signal characterization from dual-energy projection phase-stepping data with a Talbot-Lau interferometer. Sci Rep 2023; 13:767. [PMID: 36641492 PMCID: PMC9840630 DOI: 10.1038/s41598-022-27155-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/27/2022] [Indexed: 01/16/2023] Open
Abstract
Material-selective analysis of spectral X-ray imaging data requires prior knowledge of the energy dependence of the observed signal. Contrary to conventional X-ray imaging, where the material-specific attenuation coefficient is usually precisely known, the linear diffusion coefficient of the X-ray dark-field contrast does not only depend on the material and its microstructure, but also on the setup geometry and is difficult to access. Here, we present an optimization approach to retrieve the energy dependence of the X-ray dark-field signal quantitatively on the example of closed-cell foams from projection data without the need for additional hardware to a standard grating-based X-ray dark-field imaging setup. A model for the visibility is used to determine the linear diffusion coefficient with a least-squares optimization. The comparison of the results to spectrometer measurements of the linear diffusion coefficient suggests the proposed method to provide a good estimate for the energydependent dark-field signal.
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Affiliation(s)
- Kirsten Taphorn
- grid.6936.a0000000123222966Research Group Biomedical imaging Physics, Department of Physics, School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany ,grid.6936.a0000000123222966Munich Institute of Biomedical Engineering (MIBE), Technical University of Munich, 85748 Garching, Germany
| | - Lennard Kaster
- grid.6936.a0000000123222966Research Group Biomedical imaging Physics, Department of Physics, School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany ,grid.6936.a0000000123222966Munich Institute of Biomedical Engineering (MIBE), Technical University of Munich, 85748 Garching, Germany
| | - Thorsten Sellerer
- grid.6936.a0000000123222966Research Group Biomedical imaging Physics, Department of Physics, School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany ,grid.6936.a0000000123222966Munich Institute of Biomedical Engineering (MIBE), Technical University of Munich, 85748 Garching, Germany
| | - Alexander Hötger
- grid.6936.a0000000123222966Walter Schottky Institute and Physics Department, School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany ,grid.510972.80000 0005 0774 4499Munich Center for Quantum Science and Technology (MCQST), 80799 Munich, Germany
| | - Julia Herzen
- grid.6936.a0000000123222966Research Group Biomedical imaging Physics, Department of Physics, School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany ,grid.6936.a0000000123222966Munich Institute of Biomedical Engineering (MIBE), Technical University of Munich, 85748 Garching, Germany
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How YY, Morgan KS. Quantifying the x-ray dark-field signal in single-grid imaging. OPTICS EXPRESS 2022; 30:10899-10918. [PMID: 35473045 DOI: 10.1364/oe.451834] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
X-ray dark-field imaging reveals the sample microstructure that is unresolved when using conventional methods of x-ray imaging. In this paper, we derive a new method to extract and quantify the x-ray dark-field signal collected using a single-grid imaging set-up, and relate the signal strength to the number of sample microstructures, N. This was achieved by modelling sample-induced changes to the shadow of the upstream grid, and fitting experimental data to this model. Our results suggested that the dark-field scattering angle from our spherical microstructures deviates slightly from the theoretical model of N, which was consistent with results from other experimental methods. We believe the approach outlined here can equip quantitative dark-field imaging of small samples, particularly in cases where only one sample exposure is possible, either due to sample movement or radiation dose limitations. Future directions include an extension into directional dark-field imaging.
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