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Taphorn K, Mechlem K, Sellerer T, De Marco F, Viermetz M, Pfeiffer F, Pfeiffer D, Herzen J. Direct Differentiation of Pathological Changes in the Human Lung Parenchyma With Grating-Based Spectral X-ray Dark-Field Radiography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:1568-1578. [PMID: 33617451 DOI: 10.1109/tmi.2021.3061253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Diagnostic lung imaging is often associated with high radiation dose and lacks sensitivity, especially for diagnosing early stages of structural lung diseases. Therefore, diagnostic imaging methods are required which provide sound diagnosis of lung diseases with a high sensitivity as well as low patient dose. In small animal experiments, the sensitivity of grating-based X-ray dark-field imaging to structural changes in the lung tissue was demonstrated. The energy-dependence of the X-ray dark-field signal of lung tissue is a function of its microstructure and not yet known. Furthermore, conventional X-ray dark-field imaging is not capable of differentiating different types of pathological changes, such as fibrosis and emphysema. Here we demonstrate the potential diagnostic power of grating-based X-ray dark-field in combination with spectral imaging in human chest radiography for the direct differentiation of lung diseases. We investigated the energy-dependent linear diffusion coefficient of simulated lung tissue with different diseases in wave-propagation simulations and validated the results with analytical calculations. Additionally, we modeled spectral X-ray dark-field chest radiography scans to exploit these differences in energy-dependency. The results demonstrate the potential to directly differentiate structural changes in the human lung. Consequently, grating-based spectral X-ray dark-field imaging potentially contributes to the differential diagnosis of structural lung diseases at a clinically relevant dose level.
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Haggmark I, Shaker K, Hertz HM. In Silico Phase-Contrast X-Ray Imaging of Anthropomorphic Voxel-Based Phantoms. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:539-548. [PMID: 33055024 DOI: 10.1109/tmi.2020.3031318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Propagation-based phase-contrast X-ray imaging is an emerging technique that can improve dose efficiency in clinical imaging. In silico tools are key to understanding the fundamental imaging mechanisms and develop new applications. Here, due to the coherent nature of the phase-contrast effects, tools based on wave propagation (WP) are preferred over Monte Carlo (MC) based methods. WP simulations require very high wave-front sampling which typically limits simulations to small idealized objects. Virtual anthropomorphic voxel-based phantoms are typically provided with a resolution lower than imposed sampling requirements and, thus, cannot be directly translated for use in WP simulations. In the present paper we propose a general strategy to enable the use of these phantoms for WP simulations. The strategy is based on upsampling in the 3D domain followed by projection resulting in high-resolution maps of the projected thickness for each phantom material. These maps can then be efficiently used for simulations of Fresnel diffraction to generate in silico phase-contrast X-ray images. We demonstrate the strategy on an anthropomorphic breast phantom to simulate propagation-based phase-contrast mammography using a laboratory micro-focus X-ray source.
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Mechlem K, Sellerer T, Viermetz M, Herzen J, Pfeiffer F. Spectral Differential Phase Contrast X-Ray Radiography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:578-587. [PMID: 31380752 DOI: 10.1109/tmi.2019.2932450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate the combination of two emerging X-ray imaging technologies, namely spectral imaging and differential phase contrast imaging. By acquiring spatially and temporally registered images with several different X-ray spectra, spectral imaging can exploit differences in the energy-dependent attenuation to generate material selective images. Differential phase contrast imaging uses an entirely different contrast generation mechanism: The phase shift that an X-ray wave exhibits when traversing an object. As both methods can determine the (projected) electron density, we propose a novel material decomposition algorithm that uses the spectral and the phase contrast information simultaneously. Numerical experiments show that the combination of these two imaging techniques benefits from the strengths of the individual methods while the weaknesses are mitigated: Quantitatively accurate basis material images are obtained and the noise level is strongly reduced, compared to conventional spectral X-ray imaging.
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Hetterich H, Webber N, Willner M, Herzen J, Birnbacher L, Auweter S, Schüller U, Bamberg F, Notohamiprodjo S, Bartsch H, Wolf J, Marschner M, Pfeiffer F, Reiser M, Saam T. Dark-field imaging in coronary atherosclerosis. Eur J Radiol 2017; 94:38-45. [PMID: 28941758 DOI: 10.1016/j.ejrad.2017.07.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 07/21/2017] [Indexed: 02/01/2023]
Abstract
OBJECTIVES Dark-field imaging based on small angle X-ray scattering has been shown to be highly sensitive for microcalcifications, e.g. in breast tissue. We hypothesized (i) that high signal areas in dark-field imaging of atherosclerotic plaque are associated with microcalcifications and (ii) that dark-field imaging is more sensitive for microcalcifications than attenuation-based imaging. METHODS Fifteen coronary artery specimens were examined at an experimental set-up consisting of X-ray tube (40kV), grating-interferometer and detector. Tomographic dark-field-, attenuation-, and phase-contrast data were simultaneously acquired. Histopathology served as standard of reference. To explore the potential of dark field imaging in a full-body CT system, simulations were carried out with spherical calcifications of different sizes to simulate small and intermediate microcalcifications. RESULTS Microcalcifications were present in 10/10 (100%) cross-sections with high dark-field signal and without evidence of calcifications in attenuation- or phase contrast. In positive controls with high signal areas in all three modalities, 10/10 (100%) cross-sections showed macrocalcifications. In negative controls without high signal areas, no calcifications were detected. Simulations showed that the microcalcifications generate substantially higher dark-field than attenuation signal. CONCLUSIONS Dark-field imaging is highly sensitive for microcalcifications in coronary atherosclerotic plaque and might provide complementary information in the assessment of plaque instability.
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Affiliation(s)
- Holger Hetterich
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany.
| | - Nicole Webber
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Marian Willner
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Julia Herzen
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Lorenz Birnbacher
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Sigrid Auweter
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Ulrich Schüller
- Center for Neuropathology, Ludwig-Maximilians-University Hospital, Munich, Germany; Institute for Neuropathology, University Medical Center Hamburg, Germany; Department for Pediatric Hematology and Oncology, University Medical Center Hamburg, Germany
| | - Fabian Bamberg
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Susan Notohamiprodjo
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Harald Bartsch
- Institute of Pathology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Johannes Wolf
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Mathias Marschner
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Franz Pfeiffer
- Physics Department & Institute for Medical Engineering, Technical University Munich, Garching, Germany
| | - Maximilian Reiser
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
| | - Tobias Saam
- Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital, Munich, Germany
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Clare RM, Stockmar M, Dierolf M, Zanette I, Pfeiffer F. Characterization of near-field ptychography. OPTICS EXPRESS 2015; 23:19728-42. [PMID: 26367630 DOI: 10.1364/oe.23.019728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Near-field X-ray ptychography has recently been proposed and shown to be able to retrieve a sample's complex-valued transmission function from multiple near-field diffraction images each with a lateral shift of the sample and with a structured (by a diffuser) illumination [Stockmar et al. Sci Rep. 3 (2013)]. In this paper, we undertake the first investigation - via numerical simulation - of the influence of the sampling and step size of the lateral shifts, the diffuser structure size, and the propagation distance on the reconstruction of the sample's transmission function. We find that for a gold Siemens star of thickness 750 nm with typical experimental parameters, for a successful reconstruction - given a theoretical minimum of four required measurements per imaged pixel - at least six diffraction images are required.
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