| 1. |
- Hertz, Hans M., et al.
(författare)
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Propagation-based phase-contrast imaging with laboratory sources
- 2016
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Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : OSA - The Optical Society. - 9781943580095
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Konferensbidrag (refereegranskat)abstract
- We demonstrate that propagation-based phase-contrast x-ray imaging with state-of-the art laboratory microfocus sources allows imaging of thick biomedical objects with very high spatial resolution.
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| 2. |
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| 3. |
- Larsson, Daniel H., et al.
(författare)
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High-resolution short- exposure small-animal laboratory x-ray phase-contrast tomography
- 2016
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- X-ray computed tomography of small animals and their organs is an essential tool in basic and preclinical biomedical research. In both phase-contrast and absorption tomography high spatial resolution and short exposure times are of key importance. However, the observable spatial resolutions and achievable exposure times are presently limited by system parameters rather than more fundamental constraints like, e.g., dose. Here we demonstrate laboratory tomography with few-ten mu m spatial resolution and few-minute exposure time at an acceptable dose for small-animal imaging, both with absorption contrast and phase contrast. The method relies on a magnifying imaging scheme in combination with a high-power small-spot liquid-metal-jet electron-impact source. The tomographic imaging is demonstrated on intact mouse, phantoms and excised lungs, both healthy and with pulmonary emphysema.
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| 4. |
- Larsson, Jakob C., et al.
(författare)
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High-spatial-resolution nanoparticle X-ray fluorescence tomography
- 2016
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Ingår i: MEDICAL IMAGING 2016. - : SPIE. - 9781510600188
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Konferensbidrag (refereegranskat)abstract
- X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 mu m), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.
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| 5. |
- Larsson, Jakob C., et al.
(författare)
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High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles
- 2018
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 63, s. 164001-
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Tidskriftsartikel (refereegranskat)abstract
- Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.
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| 6. |
- Romell, Jenny, et al.
(författare)
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Soft-Tissue Imaging in a Human Mummy : Propagation-based Phase-Contrast CT
- 2018
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Ingår i: Radiology. - : RADIOLOGICAL SOC NORTH AMERICA. - 0033-8419 .- 1527-1315. ; 289:3, s. 670-676
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate phase-contrast CT as a noninvasive alternative to histology in the study of ancient soft tissue. Materials and Methods: The imaging was performed between May 8 and June 13, 2017. A mummified human hand from ancient Egypt was imaged in a laboratory phase-contrast CT arrangement with propagation-based imaging. The experimental arrangement for propagation-based imaging included a microfocus x-ray source, a rotation stage for the sample, and an x-ray detector. The mummified hand was imaged in two different modes. First, a CT scan of the whole hand was performed in an overview arrangement. Then, a detailed scan of the tip of the middle finger was performed. With imaging distances tailored fora large magnification and to maximize die phase-contrast signal, the estimated resolution in the final images was 6-9 mu m. Results: The overview CT allowed identification tendons of the hand, as well as identification of arteries and nerves in the dehydrated soft tissue. In the detailed phase-contrast setting, virtual histology of the soft tissues of the fingertip could be performed. Blood vessels in the nail bed and the microanatomy of the bone marrow and hypodermis were imaged, and the layers of the skin could be distinguished. Round structures in the adipose tissue were identified as the reamins of adipocytes. Conclusion: Laboratory phase-contrast CT enables imaging of the anatomy and microanatomy of mummified soft tissue with sub-10-mu m resolution and may serve as a complement or alternative to the classic invasive histrologic methods used in soft-tissue paleopathology. (C) RSNA.2018
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| 8. |
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| 9. |
- Vågberg, William, et al.
(författare)
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Removal of ring artifacts in microtomography by characterization of scintillator variations
- 2017
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Ingår i: Optics Express. - : OPTICAL SOC AMER. - 1094-4087. ; 25:19, s. 23191-23198
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Tidskriftsartikel (refereegranskat)abstract
- Ring artifacts reduce image quality in tomography, and arise from faulty detector calibration. In microtomography, we have identified that ring artifacts can arise due to highspatial frequency variations in the scintillator thickness. Such variations are normally removed by a flat-field correction. However, as the spectrum changes, e. g. due to beam hardening, the detector response varies non-uniformly introducing ring artifacts that persist after flat-field correction. In this paper, we present a method to correct for ring artifacts from variations in scintillator thickness by using a simple method to characterize the local scintillator response. The method addresses the actual physical cause of the ring artifacts, in contrary to many other ring artifact removal methods which rely only on image post-processing. By applying the technique to an experimental phantom tomography, we show that ring artifacts are strongly reduced compared to only making a flat-field correction.
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| 10. |
- Vågberg, William, et al.
(författare)
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X-ray phase-contrast tomography for high-spatial-resolution zebrafish muscle imaging
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Imaging of muscular structure with cellular or subcellular detail in whole-body animal models is of key importance for understanding muscular disease and assessing interventions. Classical histological methods for high-resolution imaging methods require excision, fixation and staining. Here we show that the three-dimensional muscular structure of unstained whole zebrafish can be imaged with sub-5μm detail with X-ray phase-contrast tomography. Our method relies on a laboratory propagation-based phase-contrast system tailored for detection of low-contrast 4-6μm subcellular myofibrils. The method is demonstrated on 20 days post fertilization zebrafish larvae and comparative histology confirms that we resolve individual myofibrils in the whole-body animal. X-ray imaging of healthy zebrafish show the expected structured muscle pattern while specimen with a dystrophin deficiency (sapje) displays an unstructured pattern, typical of Duchenne muscular dystrophy. The method opens up for whole-body imaging with sub-cellular detail also of other types of soft tissue and in different animal models.
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