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Schmid C, Viermetz M, Gustschin N, Noichl W, Haeusele J, Lasser T, Koehler T, Pfeiffer F. Modeling Vibrations of a Tiled Talbot-Lau Interferometer on a Clinical CT. IEEE TRANSACTIONS ON MEDICAL IMAGING 2023; 42:774-784. [PMID: 36301786 DOI: 10.1109/tmi.2022.3217662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
X-ray computed tomography (CT) is an invaluable imaging technique for non-invasive medical diagnosis. However, for soft tissue in the human body the difference in attenuation is inherently small. Grating-based X-ray phase-contrast is a relatively novel imaging method which detects additional interaction mechanisms between photons and matter, namely refraction and small-angle scattering, to generate additional images with different contrast. The experimental setup involves a Talbot-Lau interferometer whose susceptibility to mechanical vibrations hindered acquisition schemes suitable for clinical routine in the past. We present a processing pipeline to identify spatially and temporally variable fluctuations occurring in an interferometer installed on a continuously rotating clinical CT gantry. The correlations of the vibrations in the modular grating setup are exploited to identify a small number of relevant fluctuation modes, allowing for a sample reconstruction free of vibration artifacts.
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Tao S, Xu Y, Bai L, Tian Z, Hao X, Kuang C, Liu X. Moiré artifacts reduction in Talbot-Lau X-ray phase contrast imaging using a three-step iterative approach. OPTICS EXPRESS 2022; 30:35096-35111. [PMID: 36258469 PMCID: PMC9662601 DOI: 10.1364/oe.466277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/25/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
Talbot-Lau X-ray phase contrast imaging is a promising technique in biological imaging since it can provide absorption, differential phase contrast, and dark-field images simultaneously. However, high accuracy motorized translation stages and high stability of the imaging system are needed to avoid moiré artifacts in the reconstructed images. In this work, the effects of the stepping errors and the dose fluctuations on the transmission, differential phase contrast, and dark-field images are theoretically derived and systematically summarized. A novel three-step iterative method is designed for image reconstruction in Talbot-Lau interferometry with phase-stepping errors and dose fluctuations. Phase distributions, phase-stepping errors, and dose fluctuation coefficients are iteratively updated via the least square method until the convergence criteria are met. Moiré artifacts are mostly reduced via the proposed method in both the numerical simulations and experiments. The reconstructed images are highly coincident with the ground truth, which verifies the high accuracy of this method. The proposed algorithm is also compared with other moiré artifacts reduction algorithms, which further demonstrates the high precision of this algorithm. This work is beneficial for reducing the strict requirements for the hardware system in the conventional Talbot-Lau interferometry, such as the high accuracy motorized stages and the X-ray tube with high stability, which is significant for advancing the X-ray phase contrast imaging towards the practical medical applications.
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Affiliation(s)
- Siwei Tao
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Yueshu Xu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Ling Bai
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Zonghan Tian
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Xiang Hao
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Cuifang Kuang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, China
| | - Xu Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
- Ningbo Research Institute, Zhejiang University, Ningbo, China
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Notohamiprodjo S, Treitl KM, Hauke C, Sutter SM, Auweter S, Pfeiffer F, Reiser MF, Hellbach K. Imaging characteristics of intravascular spherical contrast agents for grating-based x-ray dark-field imaging – effects of concentrations, spherical sizes and applied voltage. Sci Rep 2020; 10:9405. [PMID: 32523085 PMCID: PMC7287139 DOI: 10.1038/s41598-020-66395-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 05/14/2020] [Indexed: 11/09/2022] Open
Abstract
AbstractThis study investigates the x-ray scattering characteristics of microsphere particles in x-ray-grating-based interferometric imaging at different concentrations, bubble sizes and tube voltages (kV). Attenuation (ATI), dark-field (DFI) and phase-contrast (PCI) images were acquired. Signal-to-noise (SNR) and contrast-to-noise ratios with water (CNRw) and air as reference (CNRa) were determined. In all modalities, a linear relationship between SNR and microbubbles concentration, respectively, microsphere size was found. A significant gain of SNR was found when varying kV. SNR was significantly higher in DFI and PCI than ATI. The highest gain of SNR was shown at 60 kV for all media in ATI and DFI, at 80 kV for PCI. SNR for all media was significantly higher compared to air and was slightly lower compared to water. A linear relationship was found between CNRa, CNRw, concentration and size. With increasing concentration and decreasing size, CNRa and CNRw increased in DFI, but decreased in PCI. Best CNRa and CNRw was found at specific combination of kV and concentration/size. Highest average CNRa and CNRw was found for microspheres in ATI and PCI, for microbubbles in DFI. Microspheres are a promising contrast-media for grating-based-interferometry, if kV, microsphere size and concentration are appropriately combined.
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Hashimoto K, Takano H, Momose A. Improved reconstruction method for phase stepping data with stepping errors and dose fluctuations. OPTICS EXPRESS 2020; 28:16363-16384. [PMID: 32549461 DOI: 10.1364/oe.385236] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/11/2020] [Indexed: 06/11/2023]
Abstract
In conventional grating-based X-ray interferometry, it is necessary to repeatedly translate one of the gratings with high accuracy in regular submicron steps and to ensure a constant dose delivery during each step. However, stepping errors and dose fluctuations inevitably occur due to mechanical inaccuracies and/or thermal drift of the interferometer during the stepping process. As a result of these stepping errors and dose fluctuations, the standard reconstruction procedure without considering them causes artifacts in the images as stripes of specific frequencies. In this report, we propose an improved reconstruction method to process phase stepping data with stepping errors and dose fluctuations. The approach can be used to estimate the stepping errors and dose fluctuations, and reconstruct virtually artifact-free images. Based on numerical simulations and experimental data including stepping errors and dose fluctuations, we demonstrate that the proposed method is more effective to other previously reported approaches.
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Chen J, Zhu J, Li Z, Shi W, Zhang Q, Hu Z, Zheng H, Liang D, Ge Y. Automatic image-domain Moiré artifact reduction method in grating-based x-ray interferometry imaging. Phys Med Biol 2019; 64:195013. [PMID: 31422959 DOI: 10.1088/1361-6560/ab3c34] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this study, we propose to remove Moiré image artifact induced by system instabilities in grating-based x-ray interferometry imaging using convolutional neural network (CNN) technique. This method reduces Moiré image artifact in image-domain via a learned image post-processing procedure, rather than developing signal retrieval optimization algorithms to minimize the inconsistencies between acquired phase stepping data and assumed signal model. To achieve this aim, we suggested to train the CNN network using dataset synthesized from both natural images and experimentally acquired Moiré artifact-only images. In particular, a novel approach is developed to generate a large number of various high quality Moiré artifact-only images from finite groups of experimental phase stepping data. Both numerical and experimental results demonstrate that the developed CNN method is able to effectively remove the undesired Moiré image artifact. As a result, the image quality of a practical grating-based x-ray interferometry system can be greatly improved.
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Affiliation(s)
- Jianwei Chen
- Research Center for Medical Artificial Intelligence, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, People's Republic of China. Equal contributions to this work and all are considered as the first authors
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Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples. Sci Rep 2019; 9:4199. [PMID: 30862865 PMCID: PMC6414610 DOI: 10.1038/s41598-018-38030-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/10/2018] [Indexed: 02/07/2023] Open
Abstract
Compared to conventional attenuation x-ray radiographic imaging, the x-ray Talbot-Lau technique provides further information about the scattering and the refractive properties of the object in the beam path. Hence, this additional information should improve the diagnostic process concerning medical applications and non-destructive testing. Nevertheless, until now, due to grating fabrication process, Talbot-Lau imaging suffers from small grating sizes (70 mm diameter). This leads to long acquisition times for imaging large objects. Stitching the gratings is one solution. Another one consists of scanning Talbot-Lau setups. In this publication, we present a compact and very fast scanning setup which enables imaging of large samples. With this setup a maximal scanning velocity of 71.7 mm/s is possible. A resolution of 4.1 lines/mm can be achieved. No complex alignment procedures are necessary while the field of view comprises 17.5 × 150 cm2. An improved reconstruction algorithm concerning the scanning approach, which increases robustness with respect to mechanical instabilities, has been developed and is presented. The resolution of the setup in dependence of the scanning velocity is evaluated. The setup imaging qualities are demonstrated using a human knee ex-vivo as an example for a high absorbing human sample.
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