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Zekavat AR, Lioliou G, Roche I Morgó O, Maughan Jones C, Galea G, Maniou E, Doherty A, Endrizzi M, Astolfo A, Olivo A, Hagen C. Phase contrast micro-CT with adjustable in-slice spatial resolution at constant magnification. Phys Med Biol 2024; 69:105017. [PMID: 38631365 DOI: 10.1088/1361-6560/ad4000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Objective.To report on a micro computed tomography (micro-CT) system capable of x-ray phase contrast imaging and of increasing spatial resolution at constant magnification.Approach.The micro-CT system implements the edge illumination (EI) method, which relies on two absorbing masks with periodically spaced transmitting apertures in the beam path; these split the beam into an array of beamlets and provide sensitivity to the beamlets' directionality, i.e. refraction. In EI, spatial resolution depends on the width of the beamlets rather than on the source/detector point spread function (PSF), meaning that resolution can be increased by decreasing the mask apertures, without changing the source/detector PSF or the magnification.Main results.We have designed a dedicated mask featuring multiple bands with differently sized apertures and used this to demonstrate that resolution is a tuneable parameter in our system, by showing that increasingly small apertures deliver increasingly detailed images. Phase contrast images of a bar pattern-based resolution phantom and a biological sample (a mouse embryo) were obtained at multiple resolutions.Significance.The new micro-CT system could find application in areas where phase contrast is already known to provide superior image quality, while the added tuneable resolution functionality could enable more sophisticated analyses in these applications, e.g. by scanning samples at multiple scales.
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Affiliation(s)
- Amir Reza Zekavat
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Grammatiki Lioliou
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Oriol Roche I Morgó
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Charlotte Maughan Jones
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Gabriel Galea
- University College London, GOS Institute of Child Health, London, United Kingdom
| | - Eirini Maniou
- University College London, GOS Institute of Child Health, London, United Kingdom
| | - Adam Doherty
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Marco Endrizzi
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Alberto Astolfo
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Alessandro Olivo
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Charlotte Hagen
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
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Brombal L, Arfelli F, Brun F, Di Trapani V, Endrizzi M, Menk RH, Perion P, Rigon L, Saccomano M, Tromba G, Olivo A. Edge-illumination spectral phase-contrast tomography. Phys Med Biol 2024; 69:075027. [PMID: 38471186 PMCID: PMC10991267 DOI: 10.1088/1361-6560/ad3328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/23/2024] [Accepted: 03/12/2024] [Indexed: 03/14/2024]
Abstract
Following the rapid, but independent, diffusion of x-ray spectral and phase-contrast systems, this work demonstrates the first combination of spectral and phase-contrast computed tomography (CT) obtained by using the edge-illumination technique and a CdTe small-pixel (62μm) spectral detector. A theoretical model is introduced, starting from a standard attenuation-based spectral decomposition and leading to spectral phase-contrast material decomposition. Each step of the model is followed by quantification of accuracy and sensitivity on experimental data of a test phantom containing different solutions with known concentrations. An example of a micro CT application (20μm voxel size) on an iodine-perfusedex vivomurine model is reported. The work demonstrates that spectral-phase contrast combines the advantages of spectral imaging, i.e. high-Zmaterial discrimination capability, and phase-contrast imaging, i.e. soft tissue sensitivity, yielding simultaneously mass density maps of water, calcium, and iodine with an accuracy of 1.1%, 3.5%, and 1.9% (root mean square errors), respectively. Results also show a 9-fold increase in the signal-to-noise ratio of the water channel when compared to standard spectral decomposition. The application to the murine model revealed the potential of the technique in the simultaneous 3D visualization of soft tissue, bone, and vasculature. While being implemented by using a broad spectrum (pink beam) at a synchrotron radiation facility (Elettra, Trieste, Italy), the proposed experimental setup can be readily translated to compact laboratory systems including conventional x-ray tubes.
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Affiliation(s)
- Luca Brombal
- Department of Physics, University of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
| | - Fulvia Arfelli
- Department of Physics, University of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
| | - Francesco Brun
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- Department of Engineering and Architecture, University of Trieste, Via A. Valerio 10, I-34127 Trieste, Italy
| | - Vittorio Di Trapani
- Department of Physics, University of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, GWC1E 6BT, London, United Kingdom
| | - Ralf H Menk
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A, I-34149 Basovizza Trieste, Italy
- Department of Computer and Electrical Engineering, Midsweden University, Holmgatan 10, Sundsvall, Sweden
| | - Paola Perion
- Department of Physics, University of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
| | - Luigi Rigon
- Department of Physics, University of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
- INFN Division of Trieste, Via A. Valerio 2, I-34127 Trieste, Italy
| | - Mara Saccomano
- Helmholtz Zentrum München, Helmholtz Pioneer Campus, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Giuliana Tromba
- Elettra-Sincrotrone Trieste S.C.p.A, I-34149 Basovizza Trieste, Italy
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, GWC1E 6BT, London, United Kingdom
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Lioliou G, Buchanan I, Astolfo A, Endrizzi M, Bate D, Hagen CK, Olivo A. Framework to optimize fixed-length micro-CT systems for propagation-based phase-contrast imaging. Opt Express 2024; 32:4839-4856. [PMID: 38439226 DOI: 10.1364/oe.510317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/11/2024] [Indexed: 03/06/2024]
Abstract
A laboratory X-ray imaging system with a setup that closely resembles commercial micro-CT systems with a fixed source-to-detector distance of ∼90 cm is investigated for single distance propagation-based phase-contrast imaging and computed tomography (CT). The system had a constant source-to-detector distance, and the sample positions were optimized. Initially, a PTFE wire was imaged, both in 2D and 3D, to characterize fringe contrast and spatial resolution for different X-ray source settings and source-to-sample distances. The results were compared to calculated values based on theoretical models and to simulated (wave-optics based) results, with good agreement being found. The optimization of the imaging system is discussed. CT scans of two biological samples, a tissue-engineered esophageal scaffold and a rat heart, were then acquired at the optimum parameters, demonstrating that significant image quality improvements can be obtained with widely available components placed inside fixed-length cabinets through proper optimization of propagation-based phase-contrast.
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Peiffer C, Brombal L, Maughan Jones CJ, Arfelli F, Astolfo A, Dreossi D, Endrizzi M, Hagen CK, Mazzolani A, Menk R, Rigon L, Olivo A, Munro PRT. On the equivalence of the X-ray scattering retrieval with beam tracking and analyser-based imaging using a synchrotron source. J Phys D Appl Phys 2023; 56:45LT02. [PMID: 37601626 PMCID: PMC10437003 DOI: 10.1088/1361-6463/acee8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/25/2023] [Accepted: 08/09/2023] [Indexed: 08/22/2023]
Abstract
X-ray phase contrast imaging (XPCI) methods give access to contrast mechanisms that are based on the refractive properties of matter on top of the absorption coefficient in conventional x-ray imaging. Ultra small angle x-ray scattering (USAXS) is a phase contrast mechanism that arises due to multiple refraction events caused by physical features of a scale below the physical resolution of the used imaging system. USAXS contrast can therefore give insight into subresolution structural information, which is an ongoing research topic in the vast field of different XPCI techniques. In this study, we quantitatively compare the USAXS signal retrieved by the beam tracking XPCI technique with the gold standard of the analyzer based imaging XPCI technique using a synchrotron x-ray source. We find that, provided certain conditions are met, the two methods measure the same quantity.
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Affiliation(s)
- C Peiffer
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - L Brombal
- Department of Physics, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
| | - C J Maughan Jones
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - F Arfelli
- Department of Physics, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
| | - A Astolfo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - D Dreossi
- Elettra Sincrotrone Trieste SCpA, S. S. 14 km 163.5, 34012 Basovizza (TS), Italy
| | - M Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - C K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - A Mazzolani
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - R Menk
- Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
- Elettra Sincrotrone Trieste SCpA, S. S. 14 km 163.5, 34012 Basovizza (TS), Italy
- Department of Computer and Electrical Engineering, Midsweden University, Sundsvall, Sweden
| | - L Rigon
- Department of Physics, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - P R T Munro
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
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Doherty A, Fourmaux S, Astolfo A, Ziesche R, Wood J, Finlay O, Stolp W, Batey D, Manke I, Légaré F, Boone M, Symes D, Najmudin Z, Endrizzi M, Olivo A, Cipiccia S. Femtosecond multimodal imaging with a laser-driven X-ray source. Commun Phys 2023; 6:288. [PMID: 38665412 PMCID: PMC11041725 DOI: 10.1038/s42005-023-01412-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/04/2023] [Indexed: 04/28/2024]
Abstract
Laser-plasma accelerators are compact linear accelerators based on the interaction of high-power lasers with plasma to form accelerating structures up to 1000 times smaller than standard radiofrequency cavities, and they come with an embedded X-ray source, namely betatron source, with unique properties: small source size and femtosecond pulse duration. A still unexplored possibility to exploit the betatron source comes from combining it with imaging methods able to encode multiple information like transmission and phase into a single-shot acquisition approach. In this work, we combine edge illumination-beam tracking (EI-BT) with a betatron X-ray source and present the demonstration of multimodal imaging (transmission, refraction, and scattering) with a compact light source down to the femtosecond timescale. The advantage of EI-BT is that it allows multimodal X-ray imaging technique, granting access to transmission, refraction and scattering signals from standard low-coherence laboratory X-ray sources in a single shot.
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Affiliation(s)
- Adam Doherty
- Department of Medical Physics and Biomedical Engineering, University College London, 2 Malet Pl, London, WC1E 7JE UK
| | - Sylvain Fourmaux
- Institut National de la Recherche Scientifique—Énergie, Matériaux et Télécommunications, Université du Québec, 1650 Lionel Boulet, Varennes, J3X 1P7 QC Canada
| | - Alberto Astolfo
- Department of Medical Physics and Biomedical Engineering, University College London, 2 Malet Pl, London, WC1E 7JE UK
| | - Ralf Ziesche
- Helmholtz-Zentrum Berlin für Materialien und Energie Hahn Meitner Platz 1, 14109 Berlin, Germany
| | - Jonathan Wood
- The John Adam Institute for Accelerator Science, Imperial College London, Prince Consort Road, South Kensington, London, SW7 2BW UK
| | - Oliver Finlay
- Central Laser Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX UK
| | - Wiebe Stolp
- UGCT-RP, Department of Physics and Astronomy, Ghent University, 9000 Ghent, Belgium
| | - Darren Batey
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX UK
| | - Ingo Manke
- Helmholtz-Zentrum Berlin für Materialien und Energie Hahn Meitner Platz 1, 14109 Berlin, Germany
| | - François Légaré
- Institut National de la Recherche Scientifique—Énergie, Matériaux et Télécommunications, Université du Québec, 1650 Lionel Boulet, Varennes, J3X 1P7 QC Canada
| | - Matthieu Boone
- UGCT-RP, Department of Physics and Astronomy, Ghent University, 9000 Ghent, Belgium
| | - Dan Symes
- Central Laser Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX UK
| | - Zulfikar Najmudin
- The John Adam Institute for Accelerator Science, Imperial College London, Prince Consort Road, South Kensington, London, SW7 2BW UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, 2 Malet Pl, London, WC1E 7JE UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, 2 Malet Pl, London, WC1E 7JE UK
| | - Silvia Cipiccia
- Department of Medical Physics and Biomedical Engineering, University College London, 2 Malet Pl, London, WC1E 7JE UK
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Esposito M, Astolfo A, Cipiccia S, Jones CM, Savvidis S, Ferrara JD, Endrizzi M, Dudhia J, Olivo A. Technical note: Cartilage imaging with sub-cellular resolution using a laboratory-based phase-contrast x-ray microscope. Med Phys 2023; 50:6130-6136. [PMID: 37431640 PMCID: PMC10947188 DOI: 10.1002/mp.16599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/10/2023] [Accepted: 06/12/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND Microscopic imaging of cartilage is a key tool for the study and development of treatments for osteoarthritis. When cellular and sub-cellular resolution is required, histology remains the gold standard approach, albeit limited by the lack of volumetric information as well as by processing artifacts. Cartilage imaging with the sub-cellular resolution has only been demonstrated in the synchrotron environment. PURPOSE To provide a proof-of-concept demonstration of the capability of a laboratory-based x-ray phase-contrast microscope to resolve sub-cellular features in a cartilage sample. METHODS This work is based on a laboratory-based x-ray microscope using intensity-modulation masks. The structured nature of the beam, resulting from the mask apertures, allows the retrieval of three contrast channels, namely, transmission, refraction and dark-field, with resolution depending only on the mask aperture width. An ex vivo equine cartilage sample was imaged with the x-ray microscope and results were validated with synchrotron tomography and histology. RESULTS Individual chondrocytes, that is, cells responsible for cartilage formation, could be detected with the laboratory-based microscope. The complementarity of the three retrieved contrast channels allowed the detection of sub-cellular features in the chondrocytes. CONCLUSIONS We provide the first proof-of-concept of imaging cartilage tissue with sub-cellular resolution using a laboratory-based x-ray microscope.
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Affiliation(s)
- Michela Esposito
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Alberto Astolfo
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Silvia Cipiccia
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Diamond Light SourceHarwell Science and Innovation CampusDidcotUK
| | | | - Savvas Savvidis
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | | | - Marco Endrizzi
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | | | - Alessandro Olivo
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
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Navarrete-León C, Doherty A, Savvidis S, Gerli MFM, Piredda G, Astolfo A, Bate D, Cipiccia S, Hagen CK, Olivo A, Endrizzi M. X-ray phase-contrast microtomography of soft tissues using a compact laboratory system with two-directional sensitivity. Optica 2023; 10:880-887. [PMID: 37841216 PMCID: PMC10575607 DOI: 10.1364/optica.487270] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/18/2023] [Accepted: 06/01/2023] [Indexed: 10/17/2023]
Abstract
X-ray microtomography is a nondestructive, three-dimensional inspection technique applied across a vast range of fields and disciplines, ranging from research to industrial, encompassing engineering, biology, and medical research. Phase-contrast imaging extends the domain of application of x-ray microtomography to classes of samples that exhibit weak attenuation, thus appearing with poor contrast in standard x-ray imaging. Notable examples are low-atomic-number materials, like carbon-fiber composites, soft matter, and biological soft tissues. We report on a compact and cost-effective system for x-ray phase-contrast microtomography. The system features high sensitivity to phase gradients and high resolution, requires a low-power sealed x-ray tube, a single optical element, and fits in a small footprint. It is compatible with standard x-ray detector technologies: in our experiments, we have observed that single-photon counting offered higher angular sensitivity, whereas flat panels provided a larger field of view. The system is benchmarked against known-material phantoms, and its potential for soft-tissue three-dimensional imaging is demonstrated on small-animal organs: a piglet esophagus and a rat heart. We believe that the simplicity of the setup we are proposing, combined with its robustness and sensitivity, will facilitate accessing quantitative x-ray phase-contrast microtomography as a research tool across disciplines, including tissue engineering, materials science, and nondestructive testing in general.
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Affiliation(s)
- Carlos Navarrete-León
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adam Doherty
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Savvas Savvidis
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Mattia F. M. Gerli
- UCL Division of Surgery and Interventional Science, Royal Free Hospital, Rowland Hill Street, London, NW3 2PF, UK
- Stem Cell and Regenerative Medicine Section, Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Giovanni Piredda
- Research Center for Microtechnology, Vorarlberg University of Applied Sciences, Hochschulstr. 1, 6850, Dornbirn, Austria
| | - Alberto Astolfo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - David Bate
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
- Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK
| | - Silvia Cipiccia
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Charlotte K. Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
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8
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Lioliou G, Navarrete-León C, Astolfo A, Savvidis S, Bate D, Endrizzi M, Hagen CK, Olivo A. A laboratory-based beam tracking x-ray imaging method achieving two-dimensional phase sensitivity and isotropic resolution with unidirectional undersampling. Sci Rep 2023; 13:8707. [PMID: 37248325 DOI: 10.1038/s41598-023-35901-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 05/25/2023] [Indexed: 05/31/2023] Open
Abstract
Beam tracking X-ray Phase Contrast Imaging is a "Shack-Hartmann" type approach which uses a pre-sample mask to split the x-rays into "beamlets" which are interrogated by a detector with sufficient resolution. The ultimate spatial resolution is determined by the size of the mask apertures, however achieving this resolution level requires "stepping" the sample or the mask in increments equal to the aperture size ("dithering"). If an array of circular apertures is used (which also provides two-dimensional phase sensitivity) instead of long parallel slits, this stepping needs to be carried out in two directions, which lengthens scan times significantly. We present a mask design obtained by offsetting rows of circular apertures, allowing for two-dimensional sensitivity and isotropic resolution while requiring sample or mask stepping in one direction only. We present images of custom-built phantoms and biological specimens, demonstrating that quantitative phase retrieval and near aperture-limited spatial resolutions are obtained in two orthogonal directions.
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Affiliation(s)
- G Lioliou
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK.
| | - C Navarrete-León
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
| | - A Astolfo
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
| | - S Savvidis
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
| | - D Bate
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
- Nikon X-Tek Systems Ltd, Tring, HP23 4JX, Herts, UK
| | - M Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
| | - C K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, London, WC1E 6BT, UK
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9
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Havariyoun G, Massimi L, Hagen CK, Endrizzi M, Olivo A. Modulation transfer function (MTF) evaluation for x-ray phase imaging system employing attenuation masks. Phys Med Biol 2023; 68. [PMID: 36996845 DOI: 10.1088/1361-6560/acc927] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 03/30/2023] [Indexed: 04/01/2023]
Abstract
OBJECTIVE Attenuation masks can be used in x-ray imaging systems to increase their inherent spatial resolution and/or make them sensitive to phase effects, a typical example being Edge Illumination X-ray phase contrast imaging (EI-XPCI). This work investigates the performance of a mask-based system such as EI-XPCI in terms of Modulation Transfer Function (MTF), in the absence of phase effects.
Approach: Pre-sampled MTF measurements, using an edge, were performed on the same system implemented without masks, with non-skipped masks and finally with skipped masks (i.e., masks in which apertures illuminate every other pixel row/column). Results are compared to simulations and finally images of a resolution bar pattern acquired with all the above setups are presented.
Main results: Compared to the detector's inherent MTF, the non-skipped mask setup provides improved MTF results. In comparison to an ideal case where signal spill-out into neighbouring pixels is negligible, this improvement takes place only at specific frequencies of the MTF, dictated by the spatial repetition of the spill-out signal. This is limited with skipped masks, which indeed provide further MTF improvements over a larger frequency range. Experimental MTF measurements are supported through simulation and resolution bar pattern images.
Significance: This work has quantified the improvement in MTF due to the use of attenuation masks and lays the foundation for how acceptance and routine quality control tests will have to be modified when systems using masks are introduced in clinical practice and how MTF results will compare to those of conventional imaging systems.
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Affiliation(s)
- Glafkos Havariyoun
- Medical Physics & Biomedical Engineering, University College London, Malet Place, Gower Street, London, WC1E 6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Lorenzo Massimi
- Medical Physics and Biomedical Engineering, University College London, Medical Physics and Biomedical Engineering, London, WC1E 6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Charlotte Klara Hagen
- Medical Physics and Bioengineering, UCL, Malet Place, Gower Street, London, London, WC1E6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Marco Endrizzi
- Department of Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, Gower Street, London, WC1E 6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Alessandro Olivo
- Department of Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, Malet Place, off Torrington Place, London, WC1E 6BT, London, WC1E 6BT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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10
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Makarova OV, Divan R, Moldovan N, Czaplewski DA, Esposito M, Endrizzi M, Tang CM, Ferrara JD, Olivo A. Freestanding high-aspect-ratio gold masks for low-energy, phase-based x-ray microscopy. Nanotechnology 2022; 34:10.1088/1361-6528/ac9b5f. [PMID: 36260979 PMCID: PMC9662782 DOI: 10.1088/1361-6528/ac9b5f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
High-resolution, x-ray phase contrast microscopy, a key technique with promising potential in biomedical imaging and diagnostics, is based on narrow-slit high-aspect-ratio gold gratings. We present the development, fabrication details, and experimental testing of the freestanding 10μm thick gold membrane masks with an array of 0.9-1.5μm void slit apertures for a novel low-energy x-ray microscope. The overall mask size is 4 mm × 4 mm, with a grating pitch of 7.5μm, 6.0-6.6μm wide gold bars are supported by 3μm wide crosslinks at 400μm intervals. The fabrication process is based on gold electroplating into a silicon mold coated with various thin films to form a voltage barrier, plating base, and sacrificial layer, followed by the mold removal to obtain the freestanding gold membrane with void slit apertures. We discuss key aspects for the materials and processes, including gold structures homogeneity, residual stresses, and prevention of collapsing of the grid elements. We further demonstrate the possibility to obtain high-resolution, high contrast 2D images of biological samples using an incoherent, rotating anode x-ray tube.
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Affiliation(s)
- Olga V Makarova
- Creatv MicroTech Inc., Chicago IL 60612, United States of America
| | - Ralu Divan
- Center for Nanoscale Materials, Argonne National Laboratory, IL 60439, United States of America
| | - Nicolaie Moldovan
- Center for Nanoscale Materials, Argonne National Laboratory, IL 60439, United States of America
- Alcorix Co, Plainfield, IL 60544, United States of America
| | - David A Czaplewski
- Center for Nanoscale Materials, Argonne National Laboratory, IL 60439, United States of America
| | - Michela Esposito
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Cha-Mei Tang
- Creatv MicroTech Inc., Potomac MD 20854, United States of America
| | - Joseph D Ferrara
- Rigaku Americas Corp, The Woodlands, TX 77371, United States of America
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
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11
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Partridge T, Astolfo A, Shankar SS, Vittoria FA, Endrizzi M, Arridge S, Riley-Smith T, Haig IG, Bate D, Olivo A. Enhanced detection of threat materials by dark-field x-ray imaging combined with deep neural networks. Nat Commun 2022; 13:4651. [PMID: 36085141 PMCID: PMC9463187 DOI: 10.1038/s41467-022-32402-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 07/29/2022] [Indexed: 11/09/2022] Open
Abstract
X-ray imaging has been boosted by the introduction of phase-based methods. Detail visibility is enhanced in phase contrast images, and dark-field images are sensitive to inhomogeneities on a length scale below the system's spatial resolution. Here we show that dark-field creates a texture which is characteristic of the imaged material, and that its combination with conventional attenuation leads to an improved discrimination of threat materials. We show that remaining ambiguities can be resolved by exploiting the different energy dependence of the dark-field and attenuation signals. Furthermore, we demonstrate that the dark-field texture is well-suited for identification through machine learning approaches through two proof-of-concept studies. In both cases, application of the same approaches to datasets from which the dark-field images were removed led to a clear degradation in performance. While the small scale of these studies means further research is required, results indicate potential for a combined use of dark-field and deep neural networks in security applications and beyond.
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Affiliation(s)
- T Partridge
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - A Astolfo
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK.,Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK
| | - S S Shankar
- Nylers Ltd, Marshall House, Middleton Road, Morden, Surrey, SM4 6RW, UK
| | - F A Vittoria
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK.,ENEA-Radiation Protection Institute, 4 Via Martiri di Monte Sole, 40129, Bologna, Italy
| | - M Endrizzi
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - S Arridge
- Department of Computer Science, UCL, London, WC1E 6BT, UK
| | - T Riley-Smith
- XPCI Technology Ltd, The Elms Courtyard, Bromesberrow, Ledbury, HR8 1RZ, UK
| | - I G Haig
- Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK
| | - D Bate
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK.,Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK.
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12
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Massimi L, Clark SJ, Marussi S, Doherty A, Shah SM, Schulz J, Marathe S, Rau C, Endrizzi M, Lee PD, Olivo A. Time resolved in-situ multi-contrast X-ray imaging of melting in metals. Sci Rep 2022; 12:12136. [PMID: 35840749 PMCID: PMC9287332 DOI: 10.1038/s41598-022-15501-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/24/2022] [Indexed: 11/30/2022] Open
Abstract
In this work, the application of a time resolved multi-contrast beam tracking technique to the investigation of the melting and solidification process in metals is presented. The use of such a technique allows retrieval of three contrast channels, transmission, refraction and dark-field, with millisecond time resolution. We investigated different melting conditions to characterize, at a proof-of-concept level, the features visible in each of the contrast channels. We found that the phase contrast channel provides a superior visibility of the density variations, allowing the liquid metal pool to be clearly distinguished. Refraction and dark-field were found to highlight surface roughness formed during solidification. This work demonstrates that the availability of the additional contrast channels provided by multi-contrast X-ray imaging delivers additional information, also when imaging high atomic number specimens with a significant absorption.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
| | - Samuel J Clark
- Department of Mechanical Engineering, University College London, Gower St, London, WC1E 6BT, UK.,X-ray Science Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL, USA
| | - Sebastian Marussi
- Department of Mechanical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Adam Doherty
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Saurabh M Shah
- Department of Mechanical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Joachim Schulz
- MicroWorks GmbH, Schnetzlerstraße 9, 76137, Karlsruhe, Germany.,Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
| | | | - Christoph Rau
- Diamond Light Source, Harwell Oxford Campus, OX11 0DE, Didcot, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Peter D Lee
- Department of Mechanical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
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13
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Esposito M, Massimi L, Buchanan I, Ferrara JD, Endrizzi M, Olivo A. A laboratory-based, low-energy, multi-modal x-ray microscope with user-defined resolution. Appl Phys Lett 2022; 120:234101. [PMID: 35693042 PMCID: PMC9183632 DOI: 10.1063/5.0082968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
We report on the development of a low-energy x-ray phase-based microscope using intensity-modulation masks for single-shot retrieval of three contrast channels: transmission, refraction, and ultra-small-angle scattering or dark field. The retrieval method is based on beam tracking, an incoherent and phase-based imaging approach. We demonstrate that the spatial resolution of this imaging system does not depend on focal spot size nor detector pixel pitch, as opposed to conventional and propagation-based x-ray imaging, and it is only dependent on the mask aperture size. This result enables the development of a multi-resolution microscope where multi-scale samples can be explored on different length scales by adjusting only the mask aperture size, without other modifications. Additionally, we show an extended capability of the system to resolve periodic structures below the resolution limit imposed by the mask apertures, which potentially extends dark-field imaging beyond its conventional use.
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Affiliation(s)
- Michela Esposito
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - Ian Buchanan
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - Joseph D. Ferrara
- Rigaku Americas Corporation, 9009 New Trails Drive, The Woodlands, Texas 77381, USA
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
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14
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Shoukroun D, Doherty A, Endrizzi M, Bate D, Fromme P, Olivo A. Post-acquisition mask misalignment correction for edge illumination x-ray phase contrast imaging. Rev Sci Instrum 2022; 93:053706. [PMID: 35649794 DOI: 10.1063/5.0090517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Edge illumination x-ray phase contrast imaging uses a set of apertured masks to translate phase effects into variation of detected intensity. While the system is relatively robust against misalignment, mask movement during acquisition can lead to gradient artifacts. A method has been developed to correct the images by quantifying the misalignment post-acquisition and implementing correction maps to remove the gradient artifact. Images of a woven carbon fiber composite plate containing porosity were used as examples to demonstrate the image correction process. The gradient formed during image acquisition was removed without affecting the image quality, and results were subsequently used for quantification of porosity, indicating that the gradient correction did not affect the quantitative content of the images.
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Affiliation(s)
- D Shoukroun
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - A Doherty
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - M Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - D Bate
- Nikon, X-Tek Systems, Ltd., Tring, Hertfordshire HP23 4JX, United Kingdom
| | - P Fromme
- Department of Mechanical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
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15
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Massimi L, Suaris T, Hagen CK, Endrizzi M, Munro PRT, Havariyoun G, Hawker PMS, Smit B, Astolfo A, Larkin OJ, Waltham RM, Shah Z, Duffy SW, Nelan RL, Peel A, Jones JL, Haig IG, Bate D, Olivo A. Volumetric High-Resolution X-Ray Phase-Contrast Virtual Histology of Breast Specimens With a Compact Laboratory System. IEEE Trans Med Imaging 2022; 41:1188-1195. [PMID: 34941505 PMCID: PMC7612751 DOI: 10.1109/tmi.2021.3137964] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The assessment of margin involvement is a fundamental task in breast conserving surgery to prevent recurrences and reoperations. It is usually performed through histology, which makes the process time consuming and can prevent the complete volumetric analysis of large specimens. X-ray phase contrast tomography combines high resolution, sufficient penetration depth and high soft tissue contrast, and can therefore provide a potential solution to this problem. In this work, we used a high-resolution implementation of the edge illumination X-ray phase contrast tomography based on "pixel-skipping" X-ray masks and sample dithering, to provide high definition virtual slices of breast specimens. The scanner was originally designed for intra-operative applications in which short scanning times were prioritised over spatial resolution; however, thanks to the versatility of edge illumination, high-resolution capabilities can be obtained with the same system simply by swapping x-ray masks without this imposing a reduction in the available field of view. This makes possible an improved visibility of fine tissue strands, enabling a direct comparison of selected CT slices with histology, and providing a tool to identify suspect features in large specimens before slicing. Combined with our previous results on fast specimen scanning, this works paves the way for the design of a multi-resolution EI scanner providing intra-operative capabilities as well as serving as a digital pathology system.
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16
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Savvidis S, Gerli MF, Pellegrini M, Massimi L, Hagen CK, Endrizzi M, Atzeni A, Ogunbiyi OK, Turmaine M, Smith ES, Fagiani C, Selmin G, Urbani L, Durkin N, Shibuya S, De Coppi P, Olivo A. Monitoring tissue engineered constructs and protocols with laboratory-based x-ray phase contrast tomography. Acta Biomater 2022; 141:290-299. [PMID: 35051630 DOI: 10.1016/j.actbio.2022.01.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/21/2021] [Accepted: 01/12/2022] [Indexed: 11/01/2022]
Abstract
Tissue engineering (TE) aims to generate bioengineered constructs which can offer a surgical treatment for many conditions involving tissue or organ loss. Construct generation must be guided by suitable assessment tools. However, most current tools (e.g. histology) are destructive, which restricts evaluation to a single-2D anatomical plane, and has no potential for assessing constructs prior to or following their implantation. An alternative can be provided by laboratory-based x-ray phase contrast computed tomography (PC-CT), which enables the extraction of 3D density maps of an organ's anatomy. In this work, we developed a semi-automated image processing pipeline dedicated to the analysis of PC-CT slices of oesophageal constructs. Visual and quantitative (density and morphological) information is extracted on a volumetric basis, enabling a comprehensive evaluation of the regenerated constructs. We believe the presented tools can enable the successful regeneration of patient-specific oesophagus, and bring comparable benefit to a wide range of TE applications. STATEMENT OF SIGNIFICANCE: Phase contrast computed tomography (PC-CT) is an imaging modality which generates high resolution volumetric density maps of biological tissue. In this work, we demonstrate the use of PC-CT as a new tool for guiding the progression of an oesophageal tissue engineering (TE) protocol. Specifically, we developed a semi-automated image-processing pipeline which analyses the oesophageal PC-CT slices, extracting visual and quantitative (density and morphological) information. This information was proven key for performing a comprehensive evaluation of the regenerated constructs, and cannot be obtained through existing assessment tools primarily due to their destructive nature (e.g. histology). This work paves the way for using PC-CT in a wide range of TE applications which can be pivotal for unlocking the potential of this field.
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17
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Astolfo A, Buchanan I, Partridge T, Kallon GK, Hagen CK, Munro PRT, Endrizzi M, Bate D, Olivo A. The effect of a variable focal spot size on the contrast channels retrieved in edge-illumination X-ray phase contrast imaging. Sci Rep 2022; 12:3354. [PMID: 35233022 PMCID: PMC8888612 DOI: 10.1038/s41598-022-07376-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 02/01/2022] [Indexed: 11/09/2022] Open
Abstract
Multi-modal X-ray imaging allows the extraction of phase and dark-field (or “Ultra-small Angle Scatter”) images alongside conventional attenuation ones. Recently, scan-based systems using conventional sources that can simultaneously output the above three images on relatively large-size objects have been developed by various groups. One limitation is the need for some degree of spatial coherence, achieved either through the use of microfocal sources, or by placing an absorption grating in front of an extended source. Both these solutions limit the amount of flux available for imaging, with the latter also leading to a more complex setup with additional alignment requirements. Edge-illumination partly overcomes this as it was proven to work with focal spots of up to 100 micron. While high-flux, 100 micron focal spot sources do exist, their comparatively large footprint and high cost can be obstacles to widespread translation. A simple solution consists in placing a single slit in front of a large focal spot source. We used a tunable slit to study the system performance at various effective focal spot sizes, by extracting transmission, phase and dark-field images of the same specimens for a range of slit widths. We show that consistent, repeatable results are obtained for varying X-ray statistics and effective focal spot sizes. As the slit width is increased, the expected reduction in the raw differential phase peaks is observed, compensated for in the retrieval process by a broadened sensitivity function. This leads to the same values being correctly retrieved, but with a slightly larger error bar i.e. a reduction in phase sensitivity. Concurrently, a slight increase in the dark-field signal is also observed.
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Affiliation(s)
- A Astolfo
- Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK.,Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - I Buchanan
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - T Partridge
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - G K Kallon
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - C K Hagen
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - P R T Munro
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - M Endrizzi
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - D Bate
- Nikon X-Tek Systems Ltd, Tring, Herts, HP23 4JX, UK.,Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, UCL, London, WC1E 6BT, UK.
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18
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Esposito M, Massimi L, Buchanan I, Ferrara JD, Endrizzi M, Olivo A. Test and optimisation of a multi-modal phase-based x-ray microscope for soft tissue imaging. Proc SPIE Int Soc Opt Eng 2022; 12031:1203102. [PMID: 36567972 PMCID: PMC9783294 DOI: 10.1117/12.2609441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M. Esposito
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - L. Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - I. Buchanan
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - J. D. Ferrara
- Rigaku Americas Corporation, 9009 New Trails Drive, The Woodlands, Texas 77381, US
| | - M. Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - A. Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
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19
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Massimi L, Clark SJ, Marussi S, Doherty A, Schulz J, Marathe S, Rau C, Endrizzi M, Lee PD, Olivo A. Dynamic Multicontrast X-Ray Imaging Method Applied to Additive Manufacturing. Phys Rev Lett 2021; 127:215503. [PMID: 34860108 DOI: 10.1103/physrevlett.127.215503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/06/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
We present a dynamic implementation of the beam-tracking x-ray imaging method providing absorption, phase, and ultrasmall angle scattering signals with microscopic resolution and high frame rate. We demonstrate the method's ability to capture dynamic processes with 22-ms time resolution by investigating the melting of metals in laser additive manufacturing, which has so far been limited to single-modality synchrotron radiography. The simultaneous availability of three contrast channels enables earlier segmentation of droplets, tracking of powder dynamic, and estimation of unfused powder amounts, demonstrating that the method can provide additional information on melting processes.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Samuel J Clark
- Department of Mechanical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Sebastian Marussi
- Department of Mechanical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Adam Doherty
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Joachim Schulz
- MicroWorks GmbH, Schnetzlerstrae 9, 76137 Karlsruhe, Germany
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Shashidhara Marathe
- Diamond Light Source, Harwell Oxford Campus, OX11 0DE Didcot, United Kingdom
| | - Christoph Rau
- Diamond Light Source, Harwell Oxford Campus, OX11 0DE Didcot, United Kingdom
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Peter D Lee
- Department of Mechanical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, United Kingdom
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20
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Massimi L, Partridge T, Astolfo A, Endrizzi M, Hagen CK, Munro PRT, Bate D, Olivo A. Optimization of multipoint phase retrieval in edge illumination X-ray imaging: A theoretical and experimental analysis. Med Phys 2021; 48:5884-5896. [PMID: 34387879 DOI: 10.1002/mp.15162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/11/2021] [Accepted: 08/03/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In this work, an analytical model describing the noise in the retrieved three contrast channels, transmission, refraction, and ultra small-angle scattering, obtained with edge illumination X-ray phase-based imaging system is presented and compared to experimental data. METHODS In EI, images acquired at different displacements of the presample mask (i.e., different illumination levels referred to as points on the "illumination curve"), followed by pixel-wise curve fitting, are exploited to quantitatively retrieve the three contrast channels. Therefore, the noise in the final image will depend on the error associated with the fitting process. We use a model based on the derivation of the standard error on fitted parameters, which relies on the calculation of the covariance matrix, to estimate the noise and the cross-channel correlation as a function of the position of the sampling points. In particular, we investigated the most common cases of 3 and 5 sampling points. In addition, simulations have been used to better understand the role of the integration time for each sampling point. Finally, the model is validated by comparison with the experimental data acquired with an edge illumination setup based on a tungsten rotating anode X-ray source and a photon counting detector. RESULTS We found a good match between the predictions of the model and the experimental data. In particular, for the investigated cases, an arrangement of the sampling points leading to minimum noise and cross-channel correlation can be found. Simulations revealed that, given a fixed overall scanning time, its distribution into the smallest possible number of sampling points needed for phase retrieval leads to minimum noise thanks to higher statistics per point. CONCLUSIONS This work presents an analytical model describing the noise in the various contrast channels retrieved in edge illumination as a function of the illumination curve sampling. In particular, an optimal sampling scheme leading to minimum noise has been determined for the case where 3 or 5 sampling points are used, which represent two of the most common acquisition schemes. In addition, the correlation between noise in the different channels and the role of the number of points and exposure time have been also investigated. In general, our results suggest a series of procedures that should be followed in order to optimize the experimental acquisitions.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Tom Partridge
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Alberto Astolfo
- Nikon X-Tek Systems Ltd., Tring Business Centre, Tring, Hertfordshire, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Charlotte K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Peter R T Munro
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - David Bate
- Nikon X-Tek Systems Ltd., Tring Business Centre, Tring, Hertfordshire, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
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21
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Roche I Morgó O, Vittoria F, Endrizzi M, Olivo A, Hagen CK. Technical Note: Practical implementation strategies of cycloidal computed tomography. Med Phys 2021; 48:6524-6530. [PMID: 34169514 DOI: 10.1002/mp.14821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 01/10/2021] [Accepted: 02/22/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Cycloidal computed tomography is a novel imaging concept which combines a highly structured x-ray beam, offset lateral under-sampling, and mathematical data recovery to obtain high-resolution images efficiently and flexibly, even with relatively large source focal spots and detector pixels. The method reduces scanning time and, potentially, delivered dose compared to other sampling schemes. This study aims to present and discuss several implementation strategies for cycloidal computed tomography (CT) in order to increase its ease of use and facilitate uptake within the imaging community. METHODS The different implementation strategies presented are step-and-shoot, continuous unidirectional, continuous back-and-forth, and continuous pixel-wise scanning. In step-and-shoot scans the sample remains stationary while frames are acquired, whereas in all other cases the sample moves through the scanner continuously. The difference between the continuous approaches is the trajectory by which the sample moves within the field of view. RESULTS All four implementation strategies are compatible with a standard table-top x-ray setup. With the experimental setup applied here, step-and-shoot acquisitions yield the best spatial resolution (around 30 µm), but are the most time-consuming (1.4 h). Continuous unidirectional and back-and-forth images have resolution between 30 and 40 µm, and are faster (35 min). Continuous pixel-wise images are equally time-efficient, although technical challenges caused a small loss in image quality with a resolution of about 50 µm. CONCLUSION The authors show that cycloidal CT can be implemented in a variety of ways with high quality results. They believe this posits cycloidal CT as a powerful imaging alternative to more time-consuming and less flexible methods in the field.
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Affiliation(s)
- Oriol Roche I Morgó
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Fabio Vittoria
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK.,ENEA Radiation Protection Institute, Bologna, Italy
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Charlotte K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
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22
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Hagen CK, Endrizzi M, Towns R, Meganck JA, Olivo A. A Preliminary Investigation into the Use of Edge Illumination X-ray Phase Contrast Micro-CT for Preclinical Imaging. Mol Imaging Biol 2021; 22:539-548. [PMID: 31250331 PMCID: PMC7250795 DOI: 10.1007/s11307-019-01396-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Purpose To enable a preliminary assessment of the suitability of edge illumination (EI) x-ray phase contrast (XPC) micro x-ray computed tomography (micro-CT) to preclinical imaging. Specifically, to understand how different acquisition schemes and their combination with dedicated data processing affect contrast-to-noise ratio (CNR) and spatial resolution, while providing control over scan time and radiation dose delivery. Procedures Deceased mice (n = 3) were scanned with an EI XPC micro-CT setup operated under different settings, leading to scan times between 18 h and 13 min. For the shortest scan, the entrance dose was measured with a calibrated PTW 23344 ion chamber. Different data processing methods were applied, retrieving either separate attenuation and phase images, or hybrid (combined attenuation and phase) images. A quantitative comparison was performed based on CNR and spatial resolution measurements for a soft tissue interface. Results All phase-based images have led to a higher CNR for the considered soft tissue interface than the attenuation image, independent of scan time. The best relative CNR (a sixfold increase) was observed in one of the hybrid images. Spatial resolution was found to be connected to scan time, with a resolution of approximately 20 μm and 60 μm achieved for the longest and shortest scans, respectively. An entrance dose of approximately 300 mGy was estimated for the scan performed within 13 min. Conclusions Despite their preliminary nature, our results suggest that EI XPC bears potential for enhancing the utility of preclinical micro-CT, and, pending further research and development, could ultimately become a valuable technique in this field.
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Affiliation(s)
- Charlotte K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Rebecca Towns
- Biological Services, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jeffrey A Meganck
- Research and Development, Life Sciences Technology, PerkinElmer, 68 Elm St, Hopkinton, MA, 01748, USA
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
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23
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Massimi L, Savvidis S, Endrizzi M, Olivo A. Improved visualization of X-ray phase contrast volumetric data through artifact-free integrated differential images. Phys Med 2021; 84:80-84. [PMID: 33878654 DOI: 10.1016/j.ejmp.2021.03.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 03/12/2021] [Accepted: 03/20/2021] [Indexed: 10/21/2022] Open
Abstract
Artifacts arising when differential phase images are integrated is a common problem to several X-ray phase-based experimental techniques. The combination of noise and insufficient sampling of the high-frequency differential phase signal leads to the formation of streak artifacts in the projections, translating into poor image quality in the tomography slices. In this work, we apply a non-iterative integration algorithm proven to reduce streak artifacts in planar (2D) images to a differential phase tomography scan. We report on how the reduction of streak artifacts in the projections improves the quality of the tomography slices, especially in the directions different from the reconstruction plane. Importantly, the method is compatible with large tomography datasets in terms of computation time.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK.
| | - Savvas Savvidis
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London WC1E 6BT, UK
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24
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Massimi L, Suaris T, Hagen CK, Endrizzi M, Munro PRT, Havariyoun G, Hawker PMS, Smit B, Astolfo A, Larkin OJ, Waltham RM, Shah Z, Duffy SW, Nelan RL, Peel A, Jones JL, Haig IG, Bate D, Olivo A. Detection of involved margins in breast specimens with X-ray phase-contrast computed tomography. Sci Rep 2021; 11:3663. [PMID: 33574584 PMCID: PMC7878478 DOI: 10.1038/s41598-021-83330-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 02/01/2021] [Indexed: 01/19/2023] Open
Abstract
Margins of wide local excisions in breast conserving surgery are tested through histology, which can delay results by days and lead to second operations. Detection of margin involvement intraoperatively would allow the removal of additional tissue during the same intervention. X-ray phase contrast imaging (XPCI) provides soft tissue sensitivity superior to conventional X-rays: we propose its use to detect margin involvement intraoperatively. We have developed a system that can perform phase-based computed tomography (CT) scans in minutes, used it to image 101 specimens approximately half of which contained neoplastic lesions, and compared results against those of a commercial system. Histological analysis was carried out on all specimens and used as the gold standard. XPCI-CT showed higher sensitivity (83%, 95% CI 69–92%) than conventional specimen imaging (32%, 95% CI 20–49%) for detection of lesions at margin, and comparable specificity (83%, 95% CI 70–92% vs 86%, 95% CI 73–93%). Within the limits of this study, in particular that specimens obtained from surplus tissue typically contain small lesions which makes detection more difficult for both methods, we believe it likely that the observed increase in sensitivity will lead to a comparable reduction in the number of re-operations.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Tamara Suaris
- St Bartholomew's Hospital, Barts Health NHS Trust, West Smithfields, London, EC1A 7BE, UK
| | - Charlotte K Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Peter R T Munro
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - Glafkos Havariyoun
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK
| | - P M Sam Hawker
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Bennie Smit
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Alberto Astolfo
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Oliver J Larkin
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Richard M Waltham
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Zoheb Shah
- Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Newark St, London, E1 2AT, UK
| | - Stephen W Duffy
- Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Newark St, London, E1 2AT, UK
| | - Rachel L Nelan
- Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Newark St, London, E1 2AT, UK
| | - Anthony Peel
- St Bartholomew's Hospital, Barts Health NHS Trust, West Smithfields, London, EC1A 7BE, UK
| | - J Louise Jones
- St Bartholomew's Hospital, Barts Health NHS Trust, West Smithfields, London, EC1A 7BE, UK.,Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Newark St, London, E1 2AT, UK
| | - Ian G Haig
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - David Bate
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way, Tring, Hertfordshire, HP23 4JX, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower St, London, WC1E 6BT, UK.
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25
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Massimi L, Buchanan I, Astolfo A, Endrizzi M, Olivo A. Fast, non-iterative algorithm for quantitative integration of X-ray differential phase-contrast images. Opt Express 2020; 28:39677-39687. [PMID: 33379512 DOI: 10.1364/oe.405755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/18/2020] [Indexed: 05/23/2023]
Abstract
X-ray phase contrast imaging is gaining importance as an imaging tool. However, it is common for X-ray phase detection techniques to be sensitive to the derivatives of the phase. Therefore, the integration of differential phase images is a fundamental step both to access quantitative pixel content and for further analysis such as segmentation. The integration of noisy data leads to artefacts with a severe impact on image quality and on its quantitative content. In this work, an integration method based on the Wiener filter is presented and tested using simulated and real data obtained with the edge illumination differential X-ray phase imaging method. The method is shown to provide high image quality while preserving the quantitative pixel content of the integrated image. In addition, it requires a short computational time making it suitable for large datasets.
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26
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Massimi L, Meganck JA, Towns R, Olivo A, Endrizzi M. Evaluation of a compact multicontrast and multiresolution X-ray phase contrast edge illumination system for small animal imaging. Med Phys 2020; 48:376-386. [PMID: 33107980 DOI: 10.1002/mp.14553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/13/2020] [Accepted: 10/18/2020] [Indexed: 01/20/2023] Open
Abstract
PURPOSE In this work the performance of a compact multiresolution and multicontrast x-ray phase system based on edge illumination is investigated. It has been designed for small animal imaging and with a limited footprint for ease of deployment in laboratories. METHODS The presented edge illumination system is based on a compact microfocus tungsten x-ray source combined with a flat panel detector. The source has a maximum output of 10 W when the minimum spot size of about 15 μm is used. The system has an overall length of 70 cm. A new double sample mask design, obtained by arranging both skipped and nonskipped configurations on the same structure, provides dual resolution capability. To test the system, we carried out computed tomography (CT) scans of a plastic phantom with different source settings using both single-image and multi-image acquisition schemes at different spatial resolutions. In addition, CT scans of an ex-vivo mouse specimen were acquired at the best identified working conditions to demonstrate the application of the presented system to small animal imaging. RESULTS We found this system delivers good image quality, allowing for an efficient material separation and improving detail visibility in small animals thanks to the higher signal-to-noise ratio (SNR) of phase contrast with respect to conventional attenuation contrast. The system offers high versatility in terms of spatial resolution thanks to the double sample mask design integrated into a single scanner. The availability of both multi- and single-image acquisition schemes coupled with their dedicated retrieval algorithms, allows different working modes which can be selected based on user preference. Multi-image acquisition provides quantitative separation of the real and imaginary part of the refractive index, however, it requires a long scanning time. On the other hand, the single image approach delivers the best material separation and image quality at all the investigated source settings with a shorter scanning time but at the cost of quantitativeness. Finally, we also observed that the single image approach combined with a high-power x-ray source may result in a fast acquisition protocol compatible with in-vivo imaging.
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Affiliation(s)
- Lorenzo Massimi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jeffrey A Meganck
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK.,Research and Development, Life Sciences Technology, PerkinElmer, Hopkinton, MA, USA
| | - Rebecca Towns
- Biological Services, University College London, Gower Street, London, WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
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27
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Buchanan I, Mittone A, Bravin A, Diemoz P, Endrizzi M, Olivo A. Simplified retrieval method for Edge Illumination X-ray phase contrast imaging allowing multi-modal imaging with fewer input frames. Opt Express 2020; 28:11597-11608. [PMID: 32403667 DOI: 10.1364/oe.372312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 02/28/2020] [Indexed: 05/23/2023]
Abstract
We present data from an implementation of Edge Illumination (EI) that uses a detector aperture designed for increasing dynamic range, suitable for clinically relevant X-ray energies and demonstrated here using synchrotron radiation. By utilising a sufficiently large crosstalk between pixels, this implementation enables single-scan imaging for phase and absorption, and double-scan for phase, absorption and dark field imaging. The presence of the detector mask enables a direct comparison between conventional EI and beam tracking (BT), which we conduct through Monte Carlo and analytical modelling in the case of a single-scan being used for the retrieval of all three contrasts. In the present case, where the X-ray beam width is comparable to the pixel size, we provide an analysis on best-positioning of the beam on the detector for accurate signal retrieval. Further, we demonstrate an application of this method by distinguishing different concentrations of microbubbles via their dark field signals at high energy using an EI system.
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28
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Havariyoun G, Vittoria FA, Hagen CK, Basta D, Kallon GK, Endrizzi M, Massimi L, Munro P, Hawker S, Smit B, Astolfo A, Larkin OJ, Waltham RM, Shah Z, Duffy SW, Nelan RL, Peel A, Suaris T, Jones JL, Haig IG, Bate D, Olivo A. A compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast. Phys Med Biol 2019; 64:235005. [PMID: 31569079 PMCID: PMC7655119 DOI: 10.1088/1361-6560/ab4912] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/09/2019] [Accepted: 09/30/2019] [Indexed: 12/03/2022]
Abstract
A significant number of patients receiving breast-conserving surgery (BCS) for invasive carcinoma and ductal carcinoma in situ (DCIS) may need reoperation following tumor-positive margins from final histopathology tests. All current intraoperative margin assessment modalities have specific limitations. As a first step towards the development of a compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast, we prove that the system's dimensions can be reduced without affecting imaging performance. We analysed the variation in noise and contrast to noise ratio (CNR) with decreasing system length using the edge illumination x-ray phase contrast imaging setup. Two-(planar) and three-(computed tomography (CT)) dimensional imaging acquisitions of custom phantoms and a breast tissue specimen were made. Dedicated phase retrieval algorithms were used to separate refraction and absorption signals. A 'single-shot' retrieval method was also used, to retrieve thickness map images, due to its simple acquisition procedure and reduced acquisition times. Experimental results were compared to numerical simulations where appropriate. The relative contribution of dark noise signal in integrating detectors is significant for low photon count statistics acquisitions. Under constant exposure factors and magnification, a more compact system provides an increase in CNR. Superior CNR results were obtained for refraction and thickness map images when compared to absorption images. Results indicate that the 'single-shot' acquisition method is preferable for a compact CT intraoperative specimen scanner; it allows for shorter acquisition times and its combination of the absorption and refraction signals ultimately leads to a higher contrast. The first CT images of a breast specimen acquired with the compact system provided promising results when compared to those of the longer length system.
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Affiliation(s)
- Glafkos Havariyoun
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
- Author to whom correspondence should be
addressed
| | - Fabio A Vittoria
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
- Current address: ENEA- Radiation Protection Institue, 4 Via
Martiri di Monte Sole, 40129 Bologna, Italy
| | - Charlotte K Hagen
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Dario Basta
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Gibril K Kallon
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Marco Endrizzi
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Lorenzo Massimi
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Peter Munro
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Sam Hawker
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Bennie Smit
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Alberto Astolfo
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Oliver J Larkin
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Richard M Waltham
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Zoheb Shah
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Stephen W Duffy
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Rachel L Nelan
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Anthony Peel
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - Tamara Suaris
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - J Louise Jones
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - Ian G Haig
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - David Bate
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
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29
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Modregger P, Meganck J, Hagen CK, Massimi L, Olivo A, Endrizzi M. Improved iterative tomographic reconstruction for x-ray imaging with edge-illumination. Phys Med Biol 2019; 64:205008. [PMID: 31509810 DOI: 10.1088/1361-6560/ab439d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Iterative tomographic reconstruction has been established as a viable alternative for data analysis in phase-sensitive x-ray imaging based on the edge-illumination principle. However, previously published approaches did not account for drifts of optical elements during a scan, which can lead to artefacts. Up to now, the strategy to reduce these artefacts was to acquire additional intermediate flat field images, which were used to correct the sinograms. Here, we expand the theoretical model to take these effects into account and demonstrate a significant reduction of (ring)-artefacts in the final reconstructions, while allowing for a significant reduction of scan time and dose. We further improve the model by including the capability to reconstruct combined absorption and phase contrast slices, which we experimentally demonstrate to deliver improved contrast to noise ratios compared to previously employed single shot approaches.
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Affiliation(s)
- Peter Modregger
- Department of Medical Physics and Bioengineering, University College London, Gower Street, WC1E 6BT London, United Kingdom. Author to whom correspondence should be addressed
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30
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Maughan Jones CJ, Vittoria FA, Olivo A, Endrizzi M, Munro PRT. Retrieval of weak x-ray scattering using edge illumination. Opt Lett 2018; 43:3874-3877. [PMID: 30106905 DOI: 10.1364/ol.43.003874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
X-ray phase contrast imaging provides additional modes of image contrast compared to conventional attenuation-based x-ray imaging, thus providing additional structural and functional information about the sample. The edge-illumination (EI) technique has been used to provide attenuation, refraction, and scattering contrast in both biological and non-biological samples. However, the retrieval of low scattering signals by fitting a single Gaussian remains problematic, principally due to the inability of the EI system to achieve perfect dark-field illumination. We present a new retrieval method that fits three Gaussians, which successfully overcomes this limitation, and provide examples of the retrieval of such signals in highly absorbing, weakly scattering samples.
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31
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Zamir A, Hagen C, Diemoz PC, Endrizzi M, Vittoria F, Chen Y, Anastasio MA, Olivo A. Recent advances in edge illumination x-ray phase-contrast tomography. J Med Imaging (Bellingham) 2017; 4:040901. [PMID: 29057286 PMCID: PMC5641577 DOI: 10.1117/1.jmi.4.4.040901] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/21/2017] [Indexed: 11/14/2022] Open
Abstract
Edge illumination (EI) is an x-ray phase-contrast imaging technique, exploiting sensitivity to x-ray refraction to visualize features, which are often not detected by conventional absorption-based radiography. The method does not require a high degree of spatial coherence and is achromatic and, therefore, can be implemented with both synchrotron radiation and commercial x-ray tubes. Using different retrieval algorithms, information about an object's attenuation, refraction, and scattering properties can be obtained. In recent years, a theoretical framework has been developed that enables EI computed tomography (CT) and, hence, three-dimensional imaging. This review provides a summary of these advances, covering the development of different image acquisition schemes, retrieval approaches, and applications. These developments constitute an integral part in the transformation of EI CT into a widely spread imaging tool for use in a range of fields.
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Affiliation(s)
- Anna Zamir
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Charlotte Hagen
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Paul C Diemoz
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Marco Endrizzi
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Fabio Vittoria
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Yujia Chen
- Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States
| | - Mark A Anastasio
- Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States
| | - Alessandro Olivo
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
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32
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Modregger P, Kagias M, Irvine SC, Brönnimann R, Jefimovs K, Endrizzi M, Olivo A. Interpretation and Utility of the Moments of Small-Angle X-Ray Scattering Distributions. Phys Rev Lett 2017; 118:265501. [PMID: 28707948 DOI: 10.1103/physrevlett.118.265501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Indexed: 05/23/2023]
Abstract
Small angle x-ray scattering has been proven to be a valuable method for accessing structural information below the spatial resolution limit implied by direct imaging. Here, we theoretically derive the relation that links the subpixel differential phase signal provided by the sample to the moments of scattering distributions accessible by refraction sensitive x-ray imaging techniques. As an important special case we explain the scatter or dark-field contrast in terms of the sample's phase signal. Further, we establish that, for binary phase objects, the nth moment scales with the difference of the refractive index decrement to the power of n. Finally, we experimentally demonstrate the utility of the moments by quantitatively determining the particle sizes of a range of powders with a laboratory-based setup.
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Affiliation(s)
- Peter Modregger
- Department of Medical Physics and Bioengineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - Matias Kagias
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland
- Institute for Biomedical Engineering, UZH/ETH Zürich, 8092 Zürich, Switzerland
| | - Sarah C Irvine
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE Oxfordshire, United Kingdom
| | - Rolf Brönnimann
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Reliability Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
| | - Konstantins Jefimovs
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland
- Institute for Biomedical Engineering, UZH/ETH Zürich, 8092 Zürich, Switzerland
| | - Marco Endrizzi
- Department of Medical Physics and Bioengineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and Bioengineering, University College London, Gower Street, WC1E 6BT London, United Kingdom
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Endrizzi M, Vittoria FA, Rigon L, Dreossi D, Iacoviello F, Shearing PR, Olivo A. X-ray Phase-Contrast Radiography and Tomography with a Multiaperture Analyzer. Phys Rev Lett 2017; 118:243902. [PMID: 28665636 DOI: 10.1103/physrevlett.118.243902] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Indexed: 05/23/2023]
Abstract
We present a multiaperture analyzer setup for performing x-ray phase contrast imaging in planar and three-dimensional modalities. The method is based on strongly structuring the x-ray beam with an amplitude modulator, before it reaches the sample, and on a multiaperture analyzing element before detection. A multislice representation of the sample is used to establish a quantitative relation between projection images and the corresponding three-dimensional distributions, leading to successful tomographic reconstruction. Sample absorption, phase, and scattering are retrieved from the measurement of five intensity projections. The method is tested on custom-built phantoms with synchrotron radiation: sample absorption and phase can be reliably retrieved also in combination with strong scatterers, simultaneously attaining high sensitivity and dynamic range.
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Affiliation(s)
- M Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - F A Vittoria
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - L Rigon
- Physics Department, University of Trieste, Via Valerio 2, 34127 Trieste, Italy
- Istituto Nazionale di Fisica Nulceare, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
| | - D Dreossi
- Sincrotrone Trieste SCpA, S.S. 14 km 163.5, 34012 Basovizza Trieste, Italy
| | - F Iacoviello
- Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, WC1E 7JE, United Kingdom
| | - P R Shearing
- Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, WC1E 7JE, United Kingdom
| | - A Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Zamir A, Diemoz PC, Vittoria FA, Hagen CK, Endrizzi M, Olivo A. Edge illumination X-ray phase tomography of multi-material samples using a single-image phase retrieval algorithm. Opt Express 2017; 25:11984-11996. [PMID: 28788753 DOI: 10.1364/oe.25.011984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this paper we present a single-image phase retrieval algorithm for multi-material samples, developed for the edge illumination (EI) X-ray phase contrast imaging method. The theoretical derivation is provided, along with any assumptions made. The algorithm is evaluated quantitatively using both simulated and experimental results from a computed tomography (CT) scan using the EI laboratory implementation. Qualitative CT results are provided for a biological sample containing both bone and soft-tissue. Using a single EI image per projection and knowledge of the complex refractive index, the algorithm can accurately retrieve the interface between a given pair of materials. A composite CT slice can be created by splicing together multiple CT reconstructions, each retrieved for a different pair of materials.
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Diémoz PC, Vittoria FA, Hagen CK, Endrizzi M, Coan P, Bravin A, Wagner UH, Rau C, Robinson IK, Olivo A. A single-image retrieval method for edge illumination X-ray phase-contrast imaging: Application and noise analysis. Phys Med 2016; 32:1759-1764. [DOI: 10.1016/j.ejmp.2016.07.093] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/11/2016] [Accepted: 07/19/2016] [Indexed: 11/28/2022] Open
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36
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Hagen CK, Maghsoudlou P, Totonelli G, Diemoz PC, Endrizzi M, Rigon L, Menk RH, Arfelli F, Dreossi D, Brun E, Coan P, Bravin A, De Coppi P, Olivo A. High contrast microstructural visualization of natural acellular matrices by means of phase-based x-ray tomography. Sci Rep 2015; 5:18156. [PMID: 26657471 PMCID: PMC4677348 DOI: 10.1038/srep18156] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 11/13/2015] [Indexed: 11/09/2022] Open
Abstract
Acellular scaffolds obtained via decellularization are a key instrument in regenerative medicine both per se and to drive the development of future-generation synthetic scaffolds that could become available off-the-shelf. In this framework, imaging is key to the understanding of the scaffolds’ internal structure as well as their interaction with cells and other organs, including ideally post-implantation. Scaffolds of a wide range of intricate organs (esophagus, lung, liver and small intestine) were imaged with x-ray phase contrast computed tomography (PC-CT). Image quality was sufficiently high to visualize scaffold microarchitecture and to detect major anatomical features, such as the esophageal mucosal-submucosal separation, pulmonary alveoli and intestinal villi. These results are a long-sought step for the field of regenerative medicine; until now, histology and scanning electron microscopy have been the gold standard to study the scaffold structure. However, they are both destructive: hence, they are not suitable for imaging scaffolds prior to transplantation, and have no prospect for post-transplantation use. PC-CT, on the other hand, is non-destructive, 3D and fully quantitative. Importantly, not only do we demonstrate achievement of high image quality at two different synchrotron facilities, but also with commercial x-ray equipment, which makes the method available to any research laboratory.
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Affiliation(s)
- Charlotte K Hagen
- University College London, Department of Medical Physics and Biomedical Engineering, London, WC1E 6BT, United Kingdom
| | | | - Giorgia Totonelli
- University College London, Institute of Child Health, London, WC1N 1EH, United Kingdom
| | - Paul C Diemoz
- University College London, Department of Medical Physics and Biomedical Engineering, London, WC1E 6BT, United Kingdom
| | - Marco Endrizzi
- University College London, Department of Medical Physics and Biomedical Engineering, London, WC1E 6BT, United Kingdom
| | - Luigi Rigon
- University of Trieste, Department of Physics, Trieste, 34127, Italy.,Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste, 34127, Italy
| | | | - Fulvia Arfelli
- University of Trieste, Department of Physics, Trieste, 34127, Italy
| | - Diego Dreossi
- Sincrotrone Trieste SCpA, Basovizza/Trieste, 34012, Italy
| | - Emmanuel Brun
- European Synchrotron Radiation Facility, Grenoble, 38043, France
| | - Paola Coan
- Ludwig Maximilians University, Department of Physics, Garching, 85748, Germany.,Ludwig Maximilians University, Faculty of Medicine, Grosshadern-Munich, 81377, Germany
| | - Alberto Bravin
- European Synchrotron Radiation Facility, Grenoble, 38043, France
| | - Paolo De Coppi
- University College London, Institute of Child Health, London, WC1N 1EH, United Kingdom
| | - Alessandro Olivo
- University College London, Department of Medical Physics and Biomedical Engineering, London, WC1E 6BT, United Kingdom
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Vittoria FA, Endrizzi M, Diemoz PC, Zamir A, Wagner UH, Rau C, Robinson IK, Olivo A. X-ray absorption, phase and dark-field tomography through a beam tracking approach. Sci Rep 2015; 5:16318. [PMID: 26541117 PMCID: PMC4635357 DOI: 10.1038/srep16318] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/12/2015] [Indexed: 11/09/2022] Open
Abstract
We present a development of the beam-tracking approach that allows its implementation in computed tomography. One absorbing mask placed before the sample and a high resolution detector are used to track variations in the beam intensity distribution caused by the sample. Absorption, refraction, and dark-field are retrieved through a multi-Gaussian interpolation of the beam. Standard filtered back projection is used to reconstruct three dimensional maps of the real and imaginary part of the refractive index, and of the dark-field signal. While the method is here demonstrated using synchrotron radiation, its low coherence requirements suggest a possible implementation with laboratory sources.
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Affiliation(s)
- Fabio A Vittoria
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, WC1E 6BT London, United Kingdom.,Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot, United Kingdom
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, WC1E 6BT London, United Kingdom
| | - Paul C Diemoz
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, WC1E 6BT London, United Kingdom.,Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot, United Kingdom
| | - Anna Zamir
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, WC1E 6BT London, United Kingdom
| | - Ulrich H Wagner
- Diamond Light Source, Harwell Oxford Campus, OX11 0DE Didcot, United Kingdom
| | - Christoph Rau
- Diamond Light Source, Harwell Oxford Campus, OX11 0DE Didcot, United Kingdom
| | - Ian K Robinson
- Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot, United Kingdom.,London Centre for Nanotechnology, WC1H 0AH London, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, WC1E 6BT London, United Kingdom
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Basta D, Endrizzi M, Vittoria FA, Kallon GKN, Millard TPM, Diemoz PC, Olivo A. Note: Design and realization of a portable edge illumination X-ray phase contrast imaging system. Rev Sci Instrum 2015; 86:096102. [PMID: 26429489 DOI: 10.1063/1.4930238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We discuss a portable edge illumination x-ray phase contrast imaging system based on compact piezoelectric motors, which enables its transportation to different environments, e.g., hosting different x-ray source technologies. The analysis of images of standard samples reveals an angular sensitivity of 270 ± 6 nrad, which compares well with the 260 ± 10 nrad reported for previous systems based on stepper motors, demonstrating that system portability can be achieved without affecting phase sensitivity. The results can also be considered a test of the performance of the piezoelectric motors, and as such could be of interest to researchers planning their use in other imaging systems.
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Affiliation(s)
- D Basta
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - M Endrizzi
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - F A Vittoria
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - G K N Kallon
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - T P M Millard
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - P C Diemoz
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - A Olivo
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
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Diemoz PC, Vittoria FA, Hagen CK, Endrizzi M, Coan P, Brun E, Wagner UH, Rau C, Robinson IK, Bravin A, Olivo A. Single-image phase retrieval using an edge illumination X-ray phase-contrast imaging setup. J Synchrotron Radiat 2015; 22:1072-7. [PMID: 26134813 PMCID: PMC4489537 DOI: 10.1107/s1600577515008978] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/09/2015] [Indexed: 05/03/2023]
Abstract
A method is proposed which enables the retrieval of the thickness or of the projected electron density of a sample from a single input image acquired with an edge illumination phase-contrast imaging setup. The method assumes the case of a quasi-homogeneous sample, i.e. a sample with a constant ratio between the real and imaginary parts of its complex refractive index. Compared with current methods based on combining two edge illumination images acquired in different configurations of the setup, this new approach presents advantages in terms of simplicity of acquisition procedure and shorter data collection time, which are very important especially for applications such as computed tomography and dynamical imaging. Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation. The method is first theoretically derived and its conditions of applicability defined. Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities. The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.
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Affiliation(s)
- Paul C. Diemoz
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK
- Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA, UK
- Correspondence e-mail:
| | - Fabio A. Vittoria
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK
- Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA, UK
| | - Charlotte K. Hagen
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK
| | - Marco Endrizzi
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK
| | - Paola Coan
- Institute for Clinical Radiology, Ludwig-Maximilians-University, Munich 81377, Germany
- Department of Physics, Ludwig-Maximilians-University, Garching 85748, Germany
| | - Emmanuel Brun
- Department of Physics, Ludwig-Maximilians-University, Garching 85748, Germany
- European Synchrotron Radiation Facility, Grenoble 38043, France
| | - Ulrich H. Wagner
- Diamond Light Source, Harwell Oxford Campus, Didcot OX11 0DE, UK
| | - Christoph Rau
- Diamond Light Source, Harwell Oxford Campus, Didcot OX11 0DE, UK
| | - Ian K. Robinson
- Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA, UK
- London Centre for Nanotechnology, London WC1 H0AH, UK
| | - Alberto Bravin
- European Synchrotron Radiation Facility, Grenoble 38043, France
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK
- Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA, UK
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Endrizzi M, Vittoria FA, Kallon G, Basta D, Diemoz PC, Vincenzi A, Delogu P, Bellazzini R, Olivo A. Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources. Opt Express 2015; 23:16473-16480. [PMID: 26193618 DOI: 10.1364/oe.23.016473] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Compatibility with polychromatic radiation is an important requirement for an imaging system using conventional rotating anode X-ray sources. With a commercially available energy-resolving single-photon-counting detector we investigated how broadband radiation affects the performance of a multi-modal edge-illumination phase-contrast imaging system. The effect of X-ray energy on phase retrieval is presented, and the achromaticity of the method is experimentally demonstrated. Comparison with simulated measurements integrating over the energy spectrum shows that there is no significant loss of image quality due to the use of polychromatic radiation. This means that, to a good approximation, the imaging system exploits radiation in the same way at all energies typically used in hard-X-ray imaging.
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Vittoria FA, Diemoz PC, Endrizzi M, De Caro L, Wagner UH, Rau C, Robinson IK, Olivo A. Phase retrieval through a one-dimensional ptychographic engine. Opt Express 2014; 22:17281-17291. [PMID: 25090542 DOI: 10.1364/oe.22.017281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Ptychographic techniques are currently the subject of increasing scientific interest due to their capability to retrieve the complex transmission function of an object at very high resolution. However, they impose a substantial burden in terms of acquisition time and dimension of the scanned area, which limits the range of samples that can be studied. We have developed a new method that combines the ptychographic approach in one direction with Fresnel propagation in the other by employing a strongly asymmetric probe. This enables scanning the sample in one direction only, substantially reducing exposure times while covering a large field of view. This approach sacrifices ptychographic-related resolution in one direction, but removes any limitation on the probe dimension in the direction orthogonal to the scanning, enabling the scan of relatively large objects without compromising exposure times.
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Hagen CK, Munro PRT, Endrizzi M, Diemoz PC, Olivo A. Low-dose phase contrast tomography with conventional x-ray sources. Med Phys 2014; 41:070701. [DOI: 10.1118/1.4884297] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Endrizzi M, Vittoria FA, Diemoz PC, Lorenzo R, Speller RD, Wagner UH, Rau C, Robinson IK, Olivo A. Phase-contrast microscopy at high x-ray energy with a laboratory setup. Opt Lett 2014; 39:3332-3335. [PMID: 24876046 DOI: 10.1364/ol.39.003332] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on the design and realization of an x-ray imaging system for quantitative phase-contrast microscopy at high x-ray energy with laboratory-scale instrumentation. Phase and amplitude were separated quantitatively at x-ray energies up to 80 keV with micrometric spatial resolution. The accuracy of the results was tested against numerical simulations, and the spatial resolution was experimentally quantified by measuring a Siemens star phase object. This simple setup should find broad application in those areas of x-ray imaging where high energy and spatial resolution are simultaneously required and in those difficult cases where the sample contains materials with similar x-ray absorption.
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Millard TP, Endrizzi M, Diemoz PC, Hagen CK, Olivo A. Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system. Rev Sci Instrum 2014; 85:053702. [PMID: 24880377 DOI: 10.1063/1.4873328] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A Monte Carlo model of a polychromatic laboratory based (coded aperture) edge illumination x-ray phase contrast imaging system has been developed and validated against experimental data. The ability for the simulation framework to be used to model two-dimensional images is also shown. The Monte Carlo model has been developed using the McXtrace engine and is polychromatic, i.e., results are obtained through the use of the full x-ray spectrum rather than an effective energy. This type of simulation can in future be used to model imaging of objects with complex geometry, for system prototyping, as well as providing a first step towards the development of a simulation for modelling dose delivery as a part of translating the imaging technique for use in clinical environments.
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Affiliation(s)
- T P Millard
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - M Endrizzi
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - P C Diemoz
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - C K Hagen
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
| | - A Olivo
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower Street, London WC1E 6BT, United Kingdom
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Hagen CK, Diemoz PC, Endrizzi M, Rigon L, Dreossi D, Arfelli F, Lopez FCM, Longo R, Olivo A. Theory and preliminary experimental verification of quantitative edge illumination x-ray phase contrast tomography. Opt Express 2014; 22:7989-8000. [PMID: 24718174 DOI: 10.1364/oe.22.007989] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
X-ray phase contrast imaging (XPCi) methods are sensitive to phase in addition to attenuation effects and, therefore, can achieve improved image contrast for weakly attenuating materials, such as often encountered in biomedical applications. Several XPCi methods exist, most of which have already been implemented in computed tomographic (CT) modality, thus allowing volumetric imaging. The Edge Illumination (EI) XPCi method had, until now, not been implemented as a CT modality. This article provides indications that quantitative 3D maps of an object's phase and attenuation can be reconstructed from EI XPCi measurements. Moreover, a theory for the reconstruction of combined phase and attenuation maps is presented. Both reconstruction strategies find applications in tissue characterisation and the identification of faint, weakly attenuating details. Experimental results for wires of known materials and for a biological object validate the theory and confirm the superiority of the phase over conventional, attenuation-based image contrast.
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Olivo A, Gkoumas S, Endrizzi M, Hagen CK, Szafraniec MB, Diemoz PC, Munro PRT, Ignatyev K, Johnson B, Horrocks JA, Vinnicombe SJ, Jones JL, Speller RD. Low-dose phase contrast mammography with conventional x-ray sources. Med Phys 2014; 40:090701. [PMID: 24007133 DOI: 10.1118/1.4817480] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To provide an x-ray phase contrast imaging (XPCI) method working with conventional sources that could be readily translated into clinical practice. XPCI shows potential in synchrotron studies but attempts at translating it for use with conventional sources are subject to limitations in terms of field of view, stability, exposure time, and possibly most importantly, delivered dose. METHODS Following the adaptation of our "edge-illumination" XPCI technique for use with conventional x-ray sources through the use of x-ray masks, the authors have further modified the design of such masks to allow further reducing the dose delivered to the sample without affecting the phase sensitivity of the method. RESULTS The authors have built a prototype based on the new mask design and used it to image ex vivo breast tissue samples containing malignant lesions. The authors compared images acquired with this prototype to those obtained with a conventional system. The authors demonstrate and quantify image improvements, especially in terms of microcalcification detection. On calcifications detected also by the conventional system, the authors measure contrast increases from five to nine fold; calcifications and other features were also detected which are completely invisible in the conventional image. Dose measurements confirmed that the above enhancements were achieved while delivering doses compatible with clinical practice. CONCLUSIONS The authors obtained phase-related image enhancements in mammography by means of a system built with components available off-the-shelf that operates under exposure time and dose conditions compatible with clinical practice. This opens the way to a straightforward translation of phase enhanced imaging methods into clinical practice.
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Affiliation(s)
- A Olivo
- Department of Medical Physics and Bioengineering, UCL, Gower Street, London WC1E 6BT, United Kingdom.
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Diemoz PC, Endrizzi M, Bravin A, Robinson IK, Olivo A. Sensitivity of edge illumination X-ray phase-contrast imaging. Philos Trans A Math Phys Eng Sci 2014; 372:20130128. [PMID: 24470420 PMCID: PMC3900038 DOI: 10.1098/rsta.2013.0128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Recently, we developed a theoretical model that can predict the signal-to-noise ratio for edge-like features in phase-contrast images. This model was then applied for the estimation of the sensitivity of three different X-ray phase-contrast techniques: propagation-based imaging, analyser-based imaging and grating interferometry. We show here how the same formalism can be used also in the case of the edge illumination (EI) technique, providing results that are consistent with those of a recently developed method for the estimation of noise in the retrieved refraction image. The new model is then applied to calculate, in the case of a given synchrotron radiation set-up, the optimum positions of the pre-sample aperture and detector edge to maximize the sensitivity. Finally, an example of the extremely high angular resolution achievable with the EI technique is presented.
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Affiliation(s)
- P. C. Diemoz
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
- Research Complex at Harwell, Harwell Oxford Campus, Didcot OX11 0FA, UK
- e-mail:
| | - M. Endrizzi
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - A. Bravin
- European Synchrotron Radiation Facility, Grenoble 38043, France
| | - I. K. Robinson
- Research Complex at Harwell, Harwell Oxford Campus, Didcot OX11 0FA, UK
- London Centre for Nanotechnology, London WC1H 0AH, UK
| | - A. Olivo
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
- Research Complex at Harwell, Harwell Oxford Campus, Didcot OX11 0FA, UK
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48
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Marenzana M, Hagen CK, Borges PDN, Endrizzi M, Szafraniec MB, Vincent TL, Rigon L, Arfelli F, Menk RH, Olivo A. Synchrotron- and laboratory-based X-ray phase-contrast imaging for imaging mouse articular cartilage in the absence of radiopaque contrast agents. Philos Trans A Math Phys Eng Sci 2014; 372:20130127. [PMID: 24470419 PMCID: PMC3900037 DOI: 10.1098/rsta.2013.0127] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The mouse model of osteoarthritis (OA) has been recognized as the most promising research tool for the identification of new OA therapeutic targets. However, this model is currently limited by poor throughput, dependent on the extremely time-consuming histopathology assessment of the articular cartilage (AC). We have recently shown that AC in the rat tibia can be imaged both in air and in saline solution using a laboratory system based on coded-aperture X-ray phase-contrast imaging (CAXPCi). Here, we explore ways to extend the methodology for imaging the much thinner AC of the mouse, by means of gold-standard synchrotron-based phase-contrast methods. Specifically, we have used analyser-based phase-contrast micro-computed tomography (micro-CT) for its high sensitivity to faint phase changes, coupled with a high-resolution (4.5 μm pixel) detector. Healthy, diseased (four weeks post induction of OA) and artificially damaged mouse AC was imaged at the Elettra synchrotron in Trieste, Italy, using the above method. For validation, we used conventional micro-CT combined with radiopaque soft-tissue staining and standard histomorphometry. We show that mouse cartilage can be visualized correctly by means of the synchrotron method. This suggests that: (i) further developments of the laboratory-based CAXPCi system, especially in terms of pushing the resolution limits, might have the potential to resolve mouse AC ex vivo and (ii) additional improvements may lead to a new generation of CAXPCi micro-CT scanners which could be used for in vivo longitudinal pre-clinical imaging of soft tissue at resolutions impossible to achieve by current MRI technology.
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Affiliation(s)
- Massimo Marenzana
- Department of Bioengineering, Imperial College, London SW7 2AZ, UK
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7HE, UK
| | - Charlotte K. Hagen
- Department of Medical Physics and Bioengineering, UCL, London WC1E 6BT, UK
| | | | - Marco Endrizzi
- Department of Medical Physics and Bioengineering, UCL, London WC1E 6BT, UK
| | | | - Tonia L. Vincent
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7HE, UK
| | - Luigi Rigon
- Dipartimento di Fisica dell'Università degli Studi di Trieste, Via Valerio 2, Trieste 34100, Italy
| | - Fulvia Arfelli
- Dipartimento di Fisica dell'Università degli Studi di Trieste, Via Valerio 2, Trieste 34100, Italy
| | - Ralf-Hendrik Menk
- Sincrotrone Trieste SCpA, Strada Statale, Basovizza, Trieste 34149, Italy
| | - Alessandro Olivo
- Department of Medical Physics and Bioengineering, UCL, London WC1E 6BT, UK
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49
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Munro PRT, Endrizzi M, Diemoz PC, Hagen CK, Szafraniec MB, Millard TP, Zapata CE, Speller RD, Olivo A. Medicine, material science and security: the versatility of the coded-aperture approach. Philos Trans A Math Phys Eng Sci 2014; 372:20130029. [PMID: 24470413 PMCID: PMC3900034 DOI: 10.1098/rsta.2013.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The principal limitation to the widespread deployment of X-ray phase imaging in a variety of applications is probably versatility. A versatile X-ray phase imaging system must be able to work with polychromatic and non-microfocus sources (for example, those currently used in medical and industrial applications), have physical dimensions sufficiently large to accommodate samples of interest, be insensitive to environmental disturbances (such as vibrations and temperature variations), require only simple system set-up and maintenance, and be able to perform quantitative imaging. The coded-aperture technique, based upon the edge illumination principle, satisfies each of these criteria. To date, we have applied the technique to mammography, materials science, small-animal imaging, non-destructive testing and security. In this paper, we outline the theory of coded-aperture phase imaging and show an example of how the technique may be applied to imaging samples with a practically important scale.
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Affiliation(s)
- P. R. T. Munro
- Optical and Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - M. Endrizzi
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - P. C. Diemoz
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - C. K. Hagen
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - M. B. Szafraniec
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - T. P. Millard
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - C. E. Zapata
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - R. D. Speller
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
| | - A. Olivo
- Department of Medical Physics and Bioengineering, University College London, Malet Place, Gower St., London WC1E 6BT, UK
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50
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Vittoria FA, Diemoz PC, Endrizzi M, Rigon L, Lopez FC, Dreossi D, Munro PRT, Olivo A. Strategies for efficient and fast wave optics simulation of coded-aperture and other x-ray phase-contrast imaging methods. Appl Opt 2013; 52:6940-6947. [PMID: 24085208 DOI: 10.1364/ao.52.006940] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
We derive a Fourier formulation of coded-aperture x-ray phase-contrast imaging, based on the wave theory of optics in the Fresnel approximation. We use this model to develop a flexible, efficient, and general simulation algorithm that can be easily adapted to other implementations of x-ray phase contrast imaging. Likewise, the algorithm enables a simple extension to 2D aperture designs, different acquisition schemes, etc. Problems related to numerical implementation of the algorithm are analyzed in detail, and simple rules are derived that enable us to avoid or at least mitigate them. Finally, comparisons with experimental data and data obtained with a different simulation algorithm are presented to validate the model and demonstrate its advantages in practical implementations. This also enabled us to demonstrate an increase in computational speed of more than one order of magnitude over a previous algorithm.
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