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Publications (10 of 17) Show all publications
Lundström, U. (2014). Phase-Contrast X-Ray Carbon Dioxide Angiography. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Phase-Contrast X-Ray Carbon Dioxide Angiography
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Phase-contrast x-ray imaging is an emerging technology, which allows for imaging of smaller features than conventional absorption-based x-ray imaging, with lower radiation dose. Instead of the attenuation that is normally used in x-ray imaging, it utilizes the phase shift introduced by an object to the transmitted x-rays. This phase shift can change the directions of the x-rays slightly, which can be measured in a few different ways. Propagation-based phase contrast, which is the method most used in this Thesis, detects these deviations using a high-resolution imaging detector at a distance from the sample. This Thesis describes how phase-contrast x-ray imaging can be used to image the internal structures of small animals like mice and rats. A technique for imaging of very small blood vessels has been developed and analyzed. By injecting a gas, such as carbon dioxide, into the vascular system, blood vessels down to 8 µm in diameter have been visualized. This is considerably smaller than the 50 µm vessels that can be imaged using iodine-based contrast agents at radiation doses compatible with living animals. A recently invented type of x-ray source, based on a jet of liquid metal as electron-beam target, has been used and further developed for the imaging purposes of this Thesis. Such metal-jet x-ray sources provide very high x-ray flux for the small x-ray spot sizes at which they operate, something that has been crucial for the quality of the phase-contrast images acquired.

Abstract [sv]

Faskontrastavbildning med röntgenstrålning är en relativt ny teknik som gör det möjligt att avbilda mindre detaljer än vanlig absorptionsbaserad röntgen, med lägre stråldos. Där normalt dämpningen av strålningen registreras, används istället det fasskift som strålningen får då den går genom ett objekt. Detta fasskift kan få röntgenstrålarna att ändra riktning, vilket kan mätas på olika sätt. Propagationsbaserad faskontrast, som har använts mest i denna avhandling, detekterar avvikelserna i fasen med hjälp av en röntgenkamera med hög upplösning en bit bakom objektet. Denna avhandling beskriver hur faskontrast kan användas för att avbilda inre strukturer i små djur som möss och råttor. En teknik för avbildning av mycket små blodkärl har utvecklats och analyserats. Genom att injicera en gas, såsom koldioxid, in i kärlsystemet har blodkärl ner till 8 µm i diameter visualiserats. Detta är betydligt mindre än de 50 µm-kärl som kan avbildas med jodbaserade kontrastmedel vid stråldoser som går att använda på levande försöksdjur. En nyligen uppfunnen typ av röntgenkälla, som skjuter elektroner på en stråle av flytande metall, har använts och utvecklats för avbildningen i denna avhandling. Dessa metallstrålekällor ger mycket röntgenstrålning för den lilla källpunkt de har, något som varit avgörande för kvaliteten på faskontrastbilderna i denna avhandling.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. p. ix, 66
Series
TRITA-FYS, ISSN 0280-316X ; 2013:70
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-139409 (URN)978-91-7501-971-0 (ISBN)
Public defence
2014-01-31, FD5, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research
Note

QC 20140113

Available from: 2014-01-14 Created: 2014-01-13 Last updated: 2014-01-14Bibliographically approved
Lundström, U., Westermark, U. K., Larsson, D. H., Burvall, A., Arsenian Henriksson, M. & Hertz, H. M. (2014). X-ray phase contrast with injected gas for tumor microangiography. Physics in Medicine and Biology, 59(11), 2801-2811
Open this publication in new window or tab >>X-ray phase contrast with injected gas for tumor microangiography
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2014 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 59, no 11, p. 2801-2811Article in journal (Refereed) Published
Abstract [en]

We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-mu m-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-mu m-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 mu m vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.

Keywords
x-ray, phase-contrast, angiography, tumor, propagation-based, microangiography, gas
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-139504 (URN)10.1088/0031-9155/59/11/2801 (DOI)000336459000016 ()2-s2.0-84900469948 (Scopus ID)
Funder
Swedish Research CouncilSwedish Cancer Society
Note

QC 20140624. Updated from manuscript to article in journal.

Available from: 2014-01-14 Created: 2014-01-14 Last updated: 2017-12-06Bibliographically approved
Zhou, T., Lundström, U., Thüring, T., Rutishauser, S., Larsson, D. H., Stampanoni, M., . . . Burvall, A. (2013). Comparison of two x-ray phase-contrast imaging methods with a microfocus source. Optics Express, 21(25), 30183-30195
Open this publication in new window or tab >>Comparison of two x-ray phase-contrast imaging methods with a microfocus source
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2013 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 25, p. 30183-30195Article in journal (Refereed) Published
Abstract [en]

We present a comparison for high-resolution imaging with a laboratory source between grating-based (GBI) and propagation-based (PBI) x-ray phase-contrast imaging. The comparison is done through simulations and experiments using a liquid-metal-jet x-ray microfocus source. Radiation doses required for detection in projection images are simulated as a function of the diameter of a cylindrical sample. Using monochromatic radiation, simulations show a lower dose requirement for PBI for small object features and a lower dose for GBI for larger object features. Using polychromatic radiation, such as that from a laboratory microfocus source, experiments and simulations show a lower dose requirement for PBI for a large range of feature sizes. Tested on a biological sample, GBI shows higher noise levels than PBI, but its advantage of quantitative refractive index reconstruction for multi-material samples becomes apparent.

Keywords
Computed-Tomography, Grating Interferometer, Noise, Propagation, Performance, Retrieval, Signal, Jet, CT
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-139423 (URN)10.1364/OE.21.030183 (DOI)000328575700007 ()2-s2.0-84890505484 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20140113

Available from: 2014-01-13 Created: 2014-01-13 Last updated: 2017-12-06Bibliographically approved
Larsson, D. H., Lundström, U., Westermark, U. K., Arsenian Henriksson, M., Burvall, A. & Hertz, H. M. (2013). First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation. Medical physics (Lancaster), 40(2), 021909
Open this publication in new window or tab >>First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation
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2013 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 40, no 2, p. 021909-Article in journal (Refereed) Published
Abstract [en]

Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with similar to 7 mu m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 mu m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

Keywords
small-animal imaging, liquid-metal-jet, x-ray, CT, tumor demarcation, mouse
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-119468 (URN)10.1118/1.4788661 (DOI)000314727700038 ()23387757 (PubMedID)2-s2.0-84873576570 (Scopus ID)
Funder
Swedish Research CouncilVinnova
Note

QC 20130319

Available from: 2013-03-19 Created: 2013-03-14 Last updated: 2017-12-06Bibliographically approved
Zhou, T., Lundström, U., Larsson, D. H., Hertz, H. M. & Burvall, A. (2013). Low-dose phase-contrast X-ray imaging: a comparison of two methods. In: 11th International Conference On X-Ray Microscopy (XRM2012): . Paper presented at 11th International Conference on X-ray Microscopy (XRM), AUG 05-10, 2012, Shanghai, China (pp. 012041). Institute of Physics (IOP)
Open this publication in new window or tab >>Low-dose phase-contrast X-ray imaging: a comparison of two methods
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2013 (English)In: 11th International Conference On X-Ray Microscopy (XRM2012), Institute of Physics (IOP), 2013, p. 012041-Conference paper, Published paper (Refereed)
Abstract [en]

Propagation- and grating-based X-ray phase-contrast imaging methods are compared theoretically. As a prospective application of phase-contrast methods in medical or small animal imaging, carbon dioxide (CO2) angiography is the simulated task. The required dose for the observable blood vessel is compared through simulation. The result indicates that the propagation-based method requires lower dose in this application.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2013
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 463
Keywords
Interferometer
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-139245 (URN)10.1088/1742-6596/463/1/012041 (DOI)000327949000041 ()2-s2.0-84890533898 (Scopus ID)
Conference
11th International Conference on X-ray Microscopy (XRM), AUG 05-10, 2012, Shanghai, China
Note

QC 20140110

Available from: 2014-01-10 Created: 2014-01-08 Last updated: 2014-01-14Bibliographically approved
Burvall, A., Larsson, D. H., Lundström, U., Stig, F., Hallström, S. & Hertz, H. M. (2013). Phase-retrieval methods with applications in composite-material tomography. In: 11th International Conference On X-Ray Microscopy (XRM2012): . Paper presented at 11th International Conference on X-ray Microscopy (XRM), AUG 05-10, 2012, Shanghai, China (pp. 012015). Institute of Physics Publishing (IOPP)
Open this publication in new window or tab >>Phase-retrieval methods with applications in composite-material tomography
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2013 (English)In: 11th International Conference On X-Ray Microscopy (XRM2012), Institute of Physics Publishing (IOPP), 2013, p. 012015-Conference paper, Published paper (Refereed)
Abstract [en]

In-line phase-contrast x-ray imaging is emerging as a method for observing small details when the contrast in absorption x-ray imaging is low. It gives images with strong edge enhancement, and phase retrieval is necessary to obtain quantitative thickness information. In particular for tomography, clarity can be enhanced by phase retrieval, as here demonstrated on a 3D-weave reinforced composite material. Seven suitable phase-retrieval methods are identified and integrated into a single method, where each version is marked by variations in particular steps. The general method and its variations are outlined and a comparison shows which methods are most suitable in different situations.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2013
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 463
Keywords
Contrast Tomography, Formulas, Distance, Objects
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-139242 (URN)10.1088/1742-6596/463/1/012015 (DOI)000327949000015 ()2-s2.0-84891284501 (Scopus ID)
Conference
11th International Conference on X-ray Microscopy (XRM), AUG 05-10, 2012, Shanghai, China
Note

QC 20140113

Available from: 2014-01-13 Created: 2014-01-08 Last updated: 2015-03-31Bibliographically approved
Thuering, T., Zhou, T., Lundström, U., Burvall, A., Rutishauser, S., David, C., . . . Stampanoni, M. (2013). X-ray grating interferometry with a liquid-metal-jet source. Applied Physics Letters, 103(9), 091105
Open this publication in new window or tab >>X-ray grating interferometry with a liquid-metal-jet source
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2013 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 9, p. 091105-Article in journal (Refereed) Published
Abstract [en]

A liquid-metal-jet X-ray tube is used in an X-ray phase-contrast microscope based on a Talbot type grating interferometer. With a focal spot size in the range of a few microns and a photon flux of similar to 10(12) photons/s x sr, the brightness of such a source is approximately one order of magnitude higher than for a conventional microfocus source. For comparison, a standard microfocus source was used with the same grating interferometer, showing significantly increased visibility for the liquid-metal-jet arrangement. Together with the increased flux, this results in improved signal-to-noise ratio.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-129628 (URN)10.1063/1.4819766 (DOI)000323846900005 ()2-s2.0-84884176871 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20131003

Available from: 2013-10-03 Created: 2013-10-03 Last updated: 2017-12-06Bibliographically approved
Larsson, D. H., Lundström, U., Westermark, U., Takman, P., Burvall, A., Arsenian Henriksson, M. & Hertz, H. M. (2012). Small-animal tomography with a liquid-metal-jet x-ray source. In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Paper presented at Medical Imaging 2012: Physics of Medical Imaging;San Diego, CA;5 February 2012 through 8 February 2012 (pp. 83130N). SPIE - International Society for Optical Engineering, 8313
Open this publication in new window or tab >>Small-animal tomography with a liquid-metal-jet x-ray source
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2012 (English)In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83130N-Conference paper, Published paper (Refereed)
Abstract [en]

X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 μm 2 FWHM x-ray spot. The peak spectral brightness is 4 × 10 9 photons/( s × mm 2 × mrad 2 × 0.1%BW) at the 24.2 keV In K α line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2012
Series
Progress in Biomedical Optics and Imaging, ISSN 1605-7422 ; 8313
Keywords
liquid-metal-jet-anode, mouse, Small-animal imaging, tomography, x-ray
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-98179 (URN)10.1117/12.910777 (DOI)000304768000021 ()2-s2.0-84860385685 (Scopus ID)978-081948962-3 (ISBN)
Conference
Medical Imaging 2012: Physics of Medical Imaging;San Diego, CA;5 February 2012 through 8 February 2012
Note
QC 20120621Available from: 2012-06-21 Created: 2012-06-20 Last updated: 2014-01-14Bibliographically approved
Burvall, A., Lundström, U., Takman, P., Larsson, D. & Hertz, H. (2012). X-ray in-line phase retrieval for tomography. In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Paper presented at Medical Imaging 2012: Physics of Medical Imaging; San Diego, CA; 5 February 2012 through 8 February 2012 (pp. 83136A). SPIE - International Society for Optical Engineering, 8313
Open this publication in new window or tab >>X-ray in-line phase retrieval for tomography
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2012 (English)In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83136A-Conference paper, Published paper (Refereed)
Abstract [en]

Phase contrast in X-ray imaging offers imaging of fine features at lower doses than absorption. Of the phasecontrast methods in use in-line phase contrast is interesting due to its experimental simplicity, but to extract information on absorption and phase distributions from the resulting images, phase retrieval is needed. Many phase-retrieval methods suitable for different situations have been developed, but few comparisons of those methods done. We consider a sub-group of phase-retrieval methods that are suitable for tomography, i.e., that use only one exposure (for practical experimental reasons) and are non-iterative (for speed). In total we have found seven suitable methods in the literature. All, though derived in different ways under different assumptions, follow the same pattern and can be outlined as a single method where each specific version is marked by variations in particular steps. We summarize this unified approach, and give the variations of the individual methods. In addition, we outline approximations and assumptions of each method. Using this approach it is possible to conclude which specific algorithms are most suitable in specific situations and to test this based on simulated and experimental data. Ultimately, this leads to conclusions on which methods are the most suitable in different situations.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2012
Series
Progress in Biomedical Optics and Imaging, ISSN 1605-7422 ; 8313
Keywords
phase contrast, phase retrieval, tomography, X-ray imaging, Experimental data, Fine Feature, In-line, In-line phase contrast, Non-iterative, Phase contrasts, Phase distribution, Phase-contrast methods, Unified approach, Xray imaging, Information retrieval, X ray analysis, Medical imaging
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-98178 (URN)10.1117/12.906391 (DOI)000304768000211 ()2-s2.0-84860354424 (Scopus ID)978-081948962-3 (ISBN)
Conference
Medical Imaging 2012: Physics of Medical Imaging; San Diego, CA; 5 February 2012 through 8 February 2012
Note
QC 20120625Available from: 2012-06-25 Created: 2012-06-20 Last updated: 2014-01-14Bibliographically approved
Lundström, U., Larsson, D. H., Takman, P., Scott, L., Burvall, A. & Hertz, H. M. (2012). X-ray phase contrast angiography using CO 2 as contrast agent. In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Paper presented at Medical Imaging 2012: Physics of Medical Imaging;San Diego, CA;5 February 2012 through 8 February 2012 (pp. 83135J). SPIE - International Society for Optical Engineering, 8313
Open this publication in new window or tab >>X-ray phase contrast angiography using CO 2 as contrast agent
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2012 (English)In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83135J-Conference paper, Published paper (Refereed)
Abstract [en]

We investigate the possibility of using x-ray in-line phase-contrast imaging with gaseous carbon dioxide as contrast agent to visualize small blood vessels. These are difficult to image at reasonable radiation doses using the absorption of conventional iodinated contrast agents. In-line phase contrast is a method for retrieving information on the electron density of the sample as well as the absorption, by moving the detector away from the sample to let phase variations in the transmitted x-rays develop into intensity variations at the detector. Blood vessels are normally difficult to observe in phase contrast even with iodinated contrast agents as the density difference compared to most tissues is small. Carbon dioxide is a clinically accepted x-ray contrast agent. The gas is injected into the blood stream of patients to temporarily displace the blood in a region and thereby reduce the x-ray absorption in the blood vessels. This gives a large density difference which is ideal for phase-contrast imaging. We demonstrate the possibilities of the method by imaging the arterial system of a rat kidney injected with carbon dioxide. Vessels down to 23 ÎŒm in diameter are shown. The method shows potential for live small-animal imaging.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2012
Series
Progress in Biomedical Optics and Imaging, ISSN 1605-7422 ; 8313
Keywords
angiography, CO 2, phase contrast, x-ray, Arterial systems, Blood streams, Contrast agent, Density difference, In-line, In-line phase contrast, In-phase, Intensity variations, Iodinated contrast agents, Phase contrasts, Phase variation, Phase-contrast imaging, Rat kidneys, Small animal imaging, X ray phase contrast, Blood vessels, Medical imaging, Tissue, X rays, Carbon dioxide
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-98180 (URN)10.1117/12.911408 (DOI)000304768000190 ()2-s2.0-84860357542 (Scopus ID)978-081948962-3 (ISBN)
Conference
Medical Imaging 2012: Physics of Medical Imaging;San Diego, CA;5 February 2012 through 8 February 2012
Note
QC 20120621Available from: 2012-06-21 Created: 2012-06-20 Last updated: 2014-01-14Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7637-1850

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