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  • 1.
    Abbott, Rebecca
    et al.
    Northwestern Univ, IL 60611 USA.
    Peolsson, Anneli
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    West, Janne
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Elliott, James M.
    Northwestern Univ, IL 60611 USA; Univ Queensland, Australia; Zurich Univ Appl Sci, Switzerland.
    Åslund, Ulrika
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    Karlsson, Anette
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    The qualitative grading of muscle fat infiltration in whiplash using fat and water magnetic resonance imaging2018In: The spine journal, ISSN 1529-9430, E-ISSN 1878-1632, Vol. 18, no 5, p. 717-725Article in journal (Refereed)
    Abstract [en]

    BACKGROUND CONTEXT: The development of muscle fat infiltration (MFI) in the neck muscles is associated with poor functional recovery following whiplash injury. Custom software and time-consuming manual segmentation of magnetic resonance imaging (MRI) is required for quantitative analysis and presents as a barrier for clinical translation. PURPOSE: The purpose of this work was to establish a qualitative MRI measure for MFI and evaluate its ability to differentiate between individuals with severe whiplash-associated disorder (WAD), mild or moderate WAD, and healthy controls. STUDY DESIGN/SETTING: This is a cross-sectional study. PATIENT SAMPLE: Thirty-one subjects with WAD and 31 age-and sex-matched controls were recruited from an ongoing randomized controlled trial. OUTCOME MEASURES: The cervical multifidus was visually identified and segmented into eighths in the axial fat/water images (C4-C7). Muscle fat infiltration was assessed on a visual scale: 0 for no or marginal MFI, 1 for light MFI, and 2 for distinct MFI. The participants with WAD were divided in two groups: mild or moderate and severe based on Neck Disability Index % scores. METHODS: The mean regional MFI was compared between the healthy controls and each of the WAD groups using the Mann-Whitney U test. Receiver operator characteristic (ROC) analyses were carried out to evaluate the validity of the qualitative method. RESULTS: Twenty (65%) patients had mild or moderate disability and 11 (35%) were considered severe. Inter- and intra-rater reliability was excellent when grading was averaged by level or when frequency of grade II was considered. Statistically significant differences (pamp;lt;.05) in regional MFI were particularly notable between the severe WAD group and healthy controls. The ROC curve, based on detection of distinct MFI, showed an area-under-the curve of 0.768 (95% confidence interval 0.59-0.94) for discrimination of WAD participants. CONCLUSIONS: These preliminary results suggest a qualitative MRI measure for MFI is reliable and valid, and may prove useful toward the classification of WAD in radiology practice. (C) 2017 Elsevier Inc. All rights reserved.

  • 2.
    Abe, K.
    et al.
    University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan.
    Aihara, H.
    University of Tokyo, Department of Physics, Tokyo, Japan.
    Ajmi, A.
    Kyoto University, Department of Physics, Kyoto, Japan.
    Alt, C.
    ETH Zurich, Institute for Particle Physics, Zurich, Switzerland.
    Andreopoulos, C.
    STFC, Rutherford Appleton Laboratory, Harwell Oxford, and Daresbury Laboratory, Warrington, United Kingdom.
    Antonova, M.
    Aoki, S.
    Asada, Y.
    Ashida, Y.
    Atherton, A.
    Atkin, E.
    Ban, S.
    Barbato, F. C. T.
    Barbi, M.
    Barker, G. J.
    Barr, G.
    Batkiewicz, M.
    Beloshapkin, A.
    Berardi, V.
    Berns, L.
    Bhadra, S.
    Bian, J.
    Bienstock, S.
    Blondel, A.
    Bolognesi, S.
    Borg, J.
    Bourguille, B.
    Boyd, S. B.
    Brailsford, D.
    Bravar, A.
    Bron, S.
    Bronner, C.
    Avanzini, M. Buizza
    Calabria, N. F.
    Calcutt, J.
    Calland, R. G.
    Calvet, D.
    Campbell, T.
    Cao, S.
    Cartwright, S. L.
    Catanesi, M. G.
    Cervera, A.
    Chappell, A.
    Cherdack, D.
    Chikuma, N.
    Christodoulou, G.
    Cicerchia, M.
    Clifton, A.
    Cogo, G.
    Coleman, J.
    Collazuol, G.
    Coplowe, D.
    Cudd, A.
    Dabrowska, A.
    Delbart, A.
    Roeck, A. De
    Rosa, G. De
    Dealtry, T.
    Dell’acqua, A.
    Denner, P. F.
    Dennis, S. R.
    Densham, C.
    Dewhurst, D.
    Lodovico, F. Di
    Dolan, S.
    Dokania, N.
    Doqua, D.
    Drapier, O.
    Duffy, K. E.
    Dumarchez, J.
    Dunne, P. J.
    Dziewiecki, M.
    Eklund, L.
    Emery-Schrenk, S.
    Fedotov, S.
    Fernandez, P.
    Feusels, T.
    Finch, A. J.
    Fiorentini, G. A.
    Fiorillo, G.
    Fitton, M.
    Friend, M.
    Fujii, Y.
    Fujita, R.
    Fukuda, D.
    Fukuda, R.
    Fukuda, Y.
    Fusshoeller, K.
    Gendotti, A.
    Giganti, C.
    Gizzarelli, F.
    Gonin, M.
    Gorin, A.
    Gramegna, F.
    Guigue, M.
    Hadley, D. R.
    Haigh, J. T.
    Hallsjö, Sven-Patrik
    University of Glasgow, School of Physics and Astronomy, Glasgow, United Kingdom.
    Hamacher-Baumann, P.
    Hansen, D.
    Harada, J.
    Hartz, M.
    Hasegawa, T.
    Hastings, N. C.
    Hayato, Y.
    Hiramoto, A.
    Hogan, M.
    Holeczek, J.
    Iacob, F.
    Ichikawa, A. K.
    Ikeda, M.
    Imber, J.
    Ishida, T.
    Ishii, T.
    Ishitsuka, M.
    Iwai, E.
    Iwamoto, K.
    Izmaylov, A.
    Jamieson, B.
    Jiang, M.
    Johnson, S.
    Jonsson, P.
    Jung, C. K.
    Kabirnezhad, M.
    Kaboth, A. C.
    Kajita, T.
    Kakuno, H.
    Kameda, J.
    Kasetti, S.
    Kataoka, Y.
    Katori, T.
    Kearns, E.
    Khabibullin, M.
    Khotjantsev, A.
    Kikawa, T.
    Kim, H.
    King, S.
    Kisiel, J.
    Knight, A.
    Knox, A.
    Kobayashi, T.
    Koch, L.
    Konaka, A.
    Kormos, L. L.
    Korzenev, A.
    Koshio, Y.
    Kowalik, K.
    Kropp, W.
    Kudenko, Y.
    Kuribayashi, S.
    Kurjata, R.
    Kutter, T.
    Kuze, M.
    Labarga, L.
    Lagoda, J.
    Lamont, I.
    Lamoureux, M.
    Last, D.
    Laveder, M.
    Lawe, M.
    Lindner, T.
    Liptak, Z. J.
    Litchfield, R. P.
    Liu, S.
    Long, K. R.
    Longhin, A.
    Lopez, J. P.
    Ludovici, L.
    Lu, X.
    Lux, T.
    Magaletti, L.
    Magro, L.
    Mahn, K.
    Malek, M.
    Manly, S.
    Marchi, T.
    Maret, L.
    Marino, A. D.
    Martin, J. F.
    Martynenko, S.
    Maruyama, T.
    Matsubara, T.
    Matsushita, K.
    Matveev, V.
    Mauger, C.
    Mavrokoridis, K.
    Mazzucato, E.
    McCarthy, M.
    McCauley, N.
    McFarland, K. S.
    McGrew, C.
    Mefodiev, A.
    Metelko, C.
    Mezzetto, M.
    Mijakowski, P.
    Mijakowski, J.
    Minamino, A.
    Mineev, O.
    Mine, S.
    Missert, A.
    Miura, M.
    Bueno, L. Molina
    Moriyama, S.
    Morrison, J.
    Mueller, Th. A.
    Murphy, S.
    Nagai, Y.
    Nakadaira, T.
    Nakahata, M.
    Nakajima, Y.
    Nakamura, A.
    Nakamura, K. G.
    Nakamura, K.
    Nakayama, S.
    Nakaya, T.
    Nakayoshi, K.
    Nantais, C.
    Ngoc, T. V.
    Nishikawa, K.
    Nishimura, Y.
    Nonnenmacher, T.
    Nova, F.
    Novella, P.
    Nowak, J.
    Nugent, J. C.
    O’Keeffe, H. M.
    Odagawa, T.
    Ohta, R.
    Okamoto, K.
    Okumura, K.
    Okusawa, T.
    Ovsyannikova, T.
    Owen, R. A.
    Oyama, Y.
    Palladino, V.
    Paolone, V.
    Pari, M.
    Parker, W.
    Parsa, S.
    Pasternak, J.
    Pastore, C.
    Pavin, M.
    Payne, D.
    Perkin, J. D.
    Pickard, L.
    Pickering, L.
    Guerra, E. S. Pinzon
    Popov, B.
    Posiadala-Zezula, M.
    Poutissou, J. -M
    Poutissou, R.
    Pozimski, J.
    Przewlocki, P.
    Przybilsk, H.
    Quilain, B.
    Radermacher, T.
    Radicioni, E.
    Radics, B.
    Ratoff, P. N.
    Reinherz-Aronis, E.
    Riccio, C.
    Rojas, P.
    Rondio, E.
    Rossi, B.
    Roth, S.
    Rubbia, A.
    Ruggeri, A. C.
    Ruggles, C. A.
    Rychter, A.
    Sakashita, K.
    Sánchez, F.
    Schloesser, C. M.
    Scholberg, K.
    Schwehr, J.
    Scott, M.
    Seiya, Y.
    Sekiguchi, T.
    Sekiya, H.
    Sgalaberna, D.
    Shaikina, A.
    Shah, R.
    Shaikhiev, A.
    Shaker, F.
    Shaw, D.
    Shiozawa, M.
    Shirahige, T.
    Shorrock, W.
    Smirnov, A.
    Smy, M.
    Sobczyk, J. T.
    Sobel, H.
    Soler, F. J. P.
    Southwell, L.
    Spina, R.
    Steinmann, J.
    Stewart, T.
    Stowell, P.
    Suvorov, S.
    Suzuki, A.
    Suzuki, S. Y.
    Suzuki, Y.
    Swierblewski, J.
    Szeptycka, M.
    Szoldos, S.
    Sztuc, A.
    Tacik, R.
    Tada, M.
    Tajima, M.
    Takeda, A.
    Takeuchi, Y.
    Tanaka, H. K.
    Tanaka, H. A.
    Thompson, L. F.
    Toki, W.
    Tomura, T.
    Touramanis, C.
    Tsui, K.
    Tsukamoto, T.
    Tzanov, M.
    Uchida, M. A.
    Uchida, Y.
    Vagins, M.
    Van, N. H.
    Vasseur, G.
    Viant, T.
    Vilela, C.
    Wachala, T.
    Walter, C. W.
    Wang, Y.
    Wark, D.
    Wascko, M. O.
    Weber, A.
    Wendell, R.
    Wilkes, R. J.
    Wilking, M. J.
    Wilson, J. R.
    Wilson, R. J.
    Wood, K.
    Wret, C.
    Yamada, Y.
    Yamamoto, K.
    Yanagisawa, C.
    Yang, G.
    Yano, T.
    Yasutome, K.
    Yen, S.
    Yershov, N.
    Yokoyama, M.
    Yoshida, T.
    Yuan, T.
    Yu, M.
    Zalewska, A.
    Zalipska, J.
    Zambelli, L.
    Zaremba, K.
    Ziembicki, M.
    Zimmerman, E. D.
    Zito, M.
    Hamada, E.
    Higashi, N.
    Hirose, E.
    Igarashi, Y.
    Iida, M.
    Iio, M.
    Ikeno, M.
    Kimura, N.
    Kurosawa, N.
    Makida, Y.
    Nakamoto, T.
    Ogitsu, T.
    Ohhata, H.
    Okada, R.
    Okamura, T.
    Onaka, M.
    Sasaki, K.
    Shimazaki, S.
    Shoji, M.
    Sugano, M.
    Tanaka, K.
    Tanaka, M.
    Terashima, A.
    Tomaru, T.
    Uchida, T.
    Yoshida, M.
    J-PARC Neutrino Beamline Upgrade Technical Design Report2019Report (Refereed)
    Abstract [en]

    In this document, technical details of the upgrade plan of the J-PARC neutrino beamline for the extension of the T2K experiment are described. T2K has proposed to accumulate data corresponding to 2×1022 protons-on-target in the next decade, aiming at an initial observation of CP violation with 3σ or higher significance in the case of maximal CP violation. Methods to increase the neutrino beam intensity, which are necessary to achieve the proposed data increase, are described.

    Download full text (pdf)
    J-PARC Neutrino Beamline Upgrade Technical Design Report
  • 3.
    Abramian, David
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Blystad, Ida
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine.
    Eklund, Anders
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Division of Medical Informatics, Department of Biomedical Engineering Linköping University Linköping Sweden;Center for Medical Image Science and Visualization (CMIV) Linköping University Linköping Sweden;Division of Statistics & Machine Learning, Department of Computer and Information Science Linköping University Linköping Sweden.
    Evaluation of inverse treatment planning for gamma knife radiosurgery using fMRI brain activation maps as organs at risk2023In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 50, no 9, p. 5297-5311Article in journal (Refereed)
    Abstract [en]

    Background: Stereotactic radiosurgery (SRS) can be an effective primary or adjuvant treatment option for intracranial tumors. However, it carries risks of various radiation toxicities, which can lead to functional deficits for the patients. Current inverse planning algorithms for SRS provide an efficient way for sparing organs at risk (OARs) by setting maximum radiation dose constraints in the treatment planning process.Purpose: We propose using activation maps from functional MRI (fMRI) to map the eloquent regions of the brain and define functional OARs (fOARs) for Gamma Knife SRS treatment planning.Methods: We implemented a pipeline for analyzing patient fMRI data, generating fOARs from the resulting activation maps, and loading them onto the GammaPlan treatment planning software. We used the Lightning inverse planner to generate multiple treatment plans from open MRI data of five subjects, and evaluated the effects of incorporating the proposed fOARs.Results: The Lightning optimizer designs treatment plans with high conformity to the specified parameters. Setting maximum dose constraints on fOARs successfully limits the radiation dose incident on them, but can have a negative impact on treatment plan quality metrics. By masking out fOAR voxels surrounding the tumor target it is possible to achieve high quality treatment plans while controlling the radiation dose on fOARs.Conclusions: The proposed method can effectively reduce the radiation dose incident on the eloquent brain areas during Gamma Knife SRS of brain tumors.

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    fulltext
  • 4.
    Abramian, David
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Larsson, Martin
    Centre of Mathematical Sciences, Lund University, Lund, Sweden.
    Eklund, Anders
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning.
    Aganj, Iman
    Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, USA; Computer Science and Artificial Intelligence Lab, Massachusetts Institute of Technology, Cambridge, USA.
    Westin, Carl-Fredrik
    Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA.
    Behjat, Hamid
    Department of Biomedical Engineering, Lund University, Lund, Sweden; Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
    Diffusion-Informed Spatial Smoothing of fMRI Data in White Matter Using Spectral Graph Filters2021In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 237, article id 118095Article in journal (Refereed)
    Abstract [en]

    Brain activation mapping using functional magnetic resonance imaging (fMRI) has been extensively studied in brain gray matter (GM), whereas in large disregarded for probing white matter (WM). This unbalanced treatment has been in part due to controversies in relation to the nature of the blood oxygenation level-dependent (BOLD) contrast in WM and its detachability. However, an accumulating body of studies has provided solid evidence of the functional significance of the BOLD signal in WM and has revealed that it exhibits anisotropic spatio-temporal correlations and structure-specific fluctuations concomitant with those of the cortical BOLD signal. In this work, we present an anisotropic spatial filtering scheme for smoothing fMRI data in WM that accounts for known spatial constraints on the BOLD signal in WM. In particular, the spatial correlation structure of the BOLD signal in WM is highly anisotropic and closely linked to local axonal structure in terms of shape and orientation, suggesting that isotropic Gaussian filters conventionally used for smoothing fMRI data are inadequate for denoising the BOLD signal in WM. The fundamental element in the proposed method is a graph-based description of WM that encodes the underlying anisotropy observed across WM, derived from diffusion-weighted MRI data. Based on this representation, and leveraging graph signal processing principles, we design subject-specific spatial filters that adapt to a subject’s unique WM structure at each position in the WM that they are applied at. We use the proposed filters to spatially smooth fMRI data in WM, as an alternative to the conventional practice of using isotropic Gaussian filters. We test the proposed filtering approach on two sets of simulated phantoms, showcasing its greater sensitivity and specificity for the detection of slender anisotropic activations, compared to that achieved with isotropic Gaussian filters. We also present WM activation mapping results on the Human Connectome Project’s 100-unrelated subject dataset, across seven functional tasks, showing that the proposed method enables the detection of streamline-like activations within axonal bundles.

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  • 5. Order onlineBuy this publication >>
    Adolfsson, Emelie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Lithium formate EPR dosimetry for accurate measurements of absorbed dose in radiotherapy2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lithium formate has shown to be a material with properties suitable for electron paramagnetic resonance (EPR) dosimetry, among them up to 7 times higher sensitivity compared to alanine, which is a well-established EPR detector material for dose determinations in radiotherapy.

    The aim of this thesis was to further investigate the properties of lithium formate and develop the dosimetry system towards applications in radiotherapy. The intrinsic efficiency for energies of relevance to brachytherapy and the signal stability were investigated. The dosimetry system was expanded to include a smaller dosimeter model, suitable for measurements in dose gradient regions. An individual sensitivity correction method was applied to the smaller dosimeters to be able to perform dose determinations with the same precision as for the larger ones. EPR dosimetry in general is time consuming and effort was spent to optimize the signal readout procedure regarding measurement time and measurement precision.

    The system was applied in two clinical applications chosen for their high demands on the dosimetry system: 1) a dosimetry audit for external photon beam therapy and 2) dose verification measurements around a low energy HDR brachytherapy source.

    The conclusions drawn from this thesis were: dose determinations can be performed with a standard uncertainty of 1.8-2.5% using both the original size dosimeters and the new developed smaller ones. The dosimetry system is robust and useful for applications when high measurement precision and accuracy is prioritized. It is a good candidate for dosimetry audits, both in external beam therapy and brachytherapy.

    List of papers
    1. Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy
    Open this publication in new window or tab >>Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy
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    2010 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 37, no 9, p. 4946-4959Article in journal (Refereed) Published
    Abstract [en]

    PURPOSE:

    To investigate experimentally the energy dependence of the detector response of lithium formate EPR dosimeters for photon energies below 1 MeV relative to that at 60Co energies. High energy photon beams are used in calibrating dosimeters for use in brachytherapy since the absorbed dose to water can be determined with high accuracy in such beams using calibrated ion chambers and standard dosimetry protocols. In addition to any differences in mass-energy absorption properties between water and detector, variations in radiation yield (detector response) with radiation quality, caused by differences in the density of ionization in the energy imparted (LET), may exist. Knowledge of an eventual deviation in detector response with photon energy is important for attaining high accuracy in measured brachytherapy dose distributions.

    METHODS:

    Lithium formate EPR dosimeters were irradiated to known levels of air kerma in 25-250 kV x-ray beams and in 137Cs and 60Co beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free in air into values of mean absorbed dose to the detectors were made using EGSnrc MC simulations and x-ray energy spectra measured or calculated for the actual beams. The signals from the detectors were measured using EPR spectrometry. Detector response (the EPR signal per mean absorbed dose to the detector) relative to that for 60Co was determined for each beam quality.

    RESULTS:

    Significant decreases in the relative response ranging from 5% to 6% were seen for x-ray beams at tube voltages < or = 180 kV. No significant reduction in the relative response was seen for 137Cs and 250 kV x rays.

    CONCLUSIONS:

    When calibrated in 60Co or MV photon beams, corrections for the photon energy dependence of detector response are needed to achieve the highest accuracy when using lithium formate EPR dosimeters for measuring absorbed doses around brachytherapy sources emitting photons in the energy range of 20-150 keV such as 169Yb and electronic sources.

    Place, publisher, year, edition, pages
    American Association of Physicists in Medicine, 2010
    Keywords
    lithium formate EPR, brachytherapy, dosimetry, detector response, kV x rays
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-59955 (URN)10.1118/1.3475938 (DOI)000281906000046 ()20964214 (PubMedID)
    Available from: 2010-10-01 Created: 2010-10-01 Last updated: 2021-10-13Bibliographically approved
    2. Investigation of signal fading in lithium formate EPR dosimeters using a new sensitive method
    Open this publication in new window or tab >>Investigation of signal fading in lithium formate EPR dosimeters using a new sensitive method
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    2012 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 8, p. 2209-2217Article in journal (Refereed) Published
    Abstract [en]

    The aim of this study was to investigate signal fading in lithium formate electron paramagnetic resonance (EPR) dosimeters used for clinical applications in radiotherapy. A new experimental method for determination of signal fading, designed to resolve small changes in signal from slowly decaying unstable radicals, was used. Possible signal fading in lithium formate due to different storage temperatures was also tested. Air humidity was kept at a constant level of 33% throughout the experiments. The conclusion drawn from the investigations was that the EPR signal from lithium formate is stable during at least 1 month after irradiation and is not sensitive to variations in storage temperature andlt;40 degrees C when kept at a relative air humidity of 33%. This makes lithium formate a suitable dosimeter for transfer dosimetry in clinical audits.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2012
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-77095 (URN)10.1088/0031-9155/57/8/2209 (DOI)000302567100008 ()22456424 (PubMedID)
    Note

    Funding Agencies|Swedish Cancer foundation (CF)|100443|FORSS|86231|

    Available from: 2012-05-04 Created: 2012-05-04 Last updated: 2021-10-13Bibliographically approved
    3. Optimisation of an EPR dosimetry system for robust and high precision dosimetry
    Open this publication in new window or tab >>Optimisation of an EPR dosimetry system for robust and high precision dosimetry
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    2014 (English)In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 70, p. 21-28Article in journal (Refereed) Published
    Abstract [en]

    Clinical applications of electron paramagnetic resonance (EPR) dosimetry systems demand high accuracy causing time consuming analysis. The need for high spatial resolution dose measurements in regions with steep dose gradients demands small sized dosimeters. An optimization of the analysis was therefore needed to limit the time consumption. The aim of this work was to introduce a new smaller lithium formate dosimeter model (diameter reduced from standard diameter 4.5 mm to 3 mm and height from 4.8 mm to 3 mm). To compensate for reduced homogeneity in a batch of the smaller dosimeters, a method for individual sensitivity correction suitable for EPR dosimetry was tested. Sensitivity and repeatability was also tested for a standard EPR resonator and a super high Q (SHQE) one. The aim was also to optimize the performance of the dosimetry system for better efficiency regarding measurement time and precision. A systematic investigation of the relationship between measurement uncertainty and number of readouts per dosimeter was performed. The conclusions drawn from this work were that it is possible to decrease the dosimeter size with maintained measurement precision by using the SHQE resonator and introducing individual calibration factors for dosimeter batches. It was also shown that it is possible reduce the number of readouts per dosimeter without significantly decreasing the accuracy in measurements.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    EPR; ESR; Lithium formate; High precision dosimetry; High spatial resolution dosimetry
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-111088 (URN)10.1016/j.radmeas.2014.08.013 (DOI)000345110700005 ()
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2021-10-13Bibliographically approved
    4. A system for remote dosimetry audit of 3D-CRT, IMRT and VMAT based on lithium formate dosimetry
    Open this publication in new window or tab >>A system for remote dosimetry audit of 3D-CRT, IMRT and VMAT based on lithium formate dosimetry
    Show others...
    2014 (English)In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 113, no 2, p. 279-282Article in journal (Refereed) Published
    Abstract [en]

    The aim of this work was to develop and test a remote end-to-end audit system using lithium formate EPR dosimeters. Four clinics were included in a pilot study, absorbed doses determined in the PTV agreed with TPS calculated doses within ±5% for 3D-CRT and ±7% (k=1) for IMRT/VMAT dose plans.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Dosimetry audit; remote audit; end-to-end; EPR; ESR; lithium formate
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-111089 (URN)10.1016/j.radonc.2014.11.027 (DOI)000347657200021 ()
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2021-10-13Bibliographically approved
    5. Measurement of absorbed dose to water around an electronic brachytherapy source: Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film
    Open this publication in new window or tab >>Measurement of absorbed dose to water around an electronic brachytherapy source: Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film
    Show others...
    2015 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 60, no 9, p. 3869-3882Article in journal (Refereed) Published
    Abstract [en]

    Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film.

    Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water.

    Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison.

    This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies (192Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.

    Place, publisher, year, edition, pages
    Institute of Physics Publishing (IOPP), 2015
    Keywords
    Electronic brachytherapy, EPR, lithium formate, radiochromic film, intrinsic efficiency
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-111090 (URN)10.1088/0031-9155/60/9/3869 (DOI)000354104700030 ()
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2021-10-13Bibliographically approved
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    Lithium formate EPR dosimetry for accurate measurements of absorbed dose in radiotherapy
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    omslag
  • 6.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Optimisation of an EPR dosimetry system for robust and high precision dosimetry2014In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 70, p. 21-28Article in journal (Refereed)
    Abstract [en]

    Clinical applications of electron paramagnetic resonance (EPR) dosimetry systems demand high accuracy causing time consuming analysis. The need for high spatial resolution dose measurements in regions with steep dose gradients demands small sized dosimeters. An optimization of the analysis was therefore needed to limit the time consumption. The aim of this work was to introduce a new smaller lithium formate dosimeter model (diameter reduced from standard diameter 4.5 mm to 3 mm and height from 4.8 mm to 3 mm). To compensate for reduced homogeneity in a batch of the smaller dosimeters, a method for individual sensitivity correction suitable for EPR dosimetry was tested. Sensitivity and repeatability was also tested for a standard EPR resonator and a super high Q (SHQE) one. The aim was also to optimize the performance of the dosimetry system for better efficiency regarding measurement time and precision. A systematic investigation of the relationship between measurement uncertainty and number of readouts per dosimeter was performed. The conclusions drawn from this work were that it is possible to decrease the dosimeter size with maintained measurement precision by using the SHQE resonator and introducing individual calibration factors for dosimeter batches. It was also shown that it is possible reduce the number of readouts per dosimeter without significantly decreasing the accuracy in measurements.

  • 7.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Olsson, Sara
    Medical Physics and Technology, Växjö Central Hospital, Växjö, Sweden.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    A system for remote dosimetry audit of 3D-CRT, IMRT and VMAT based on lithium formate dosimetry2014In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 113, no 2, p. 279-282Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to develop and test a remote end-to-end audit system using lithium formate EPR dosimeters. Four clinics were included in a pilot study, absorbed doses determined in the PTV agreed with TPS calculated doses within ±5% for 3D-CRT and ±7% (k=1) for IMRT/VMAT dose plans.

    Download full text (pdf)
    fulltext
  • 8.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Wesolowska, Paulina
    IAEA, Austria.
    Izewska, Joanna
    IAEA, Austria.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Karolinska Univ Hosp, Sweden.
    END-TO-END AUDIT: COMPARISON OF TLD AND LITHIUM FORMATE EPR DOSIMETRY2019In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 186, no 1, p. 119-122Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to test two different solid state dosimetry systems for the purpose of end-to-end audits of radiotherapy volumetric modulated arc therapy (VMAT) technique; a lithium formate electron paramagnetic resonance system and a lithium fluoride thermoluminescent dosimetry system. As a complement to the solid state systems, ion chamber measurements were performed. A polystyrene phantom with a planning target volume (PTV) and an organ at risk (OAR) structure was scanned using CT. A VMAT dose plan was optimized to deliver 2 Gy to the target volume and to minimize the dose to the OAR. The different detectors were inserted into the phantom and the planned dose distribution was delivered. The measured doses were compared to the treatment planning system (TPS) calculated doses. Good agreement was found between the TPS calculated and the measured doses, well accepted for the dose determinations in remote dosimetry audits of VMAT treatment technique.

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    fulltext
  • 9.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    White, Shane
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Landry, Guillaume
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Verhaegen, Frank
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Reniers, Brigitte
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Measurement of absorbed dose to water around an electronic brachytherapy source: Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film2015In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 60, no 9, p. 3869-3882Article in journal (Refereed)
    Abstract [en]

    Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film.

    Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water.

    Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison.

    This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies (192Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.

  • 10.
    Ahlander, B. M.
    et al.
    Ryhov County Hospital, Jönköping, Sweden.
    Engvall, Jan
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Heart Center, Department of Clinical Physiology in Linköping.
    Ericsson, E.
    Faculty of Medicine and Health, School of Health Science, Örebro University, Örebro, Sweden.
    Anxiety during magnetic resonance imaging of the spine in relation to scanner design and size2020In: Radiography, ISSN 1078-8174, E-ISSN 1532-2831, Vol. 26, no 2, p. 110-116Article in journal (Refereed)
    Abstract [en]

    Introduction: Magnetic resonance imaging in closed-bore scanners sometimes provokes anxiety but closed-bore designs have gradually become wider and shorter. Open scanners may be easier to tolerate. The aim was to compare patient anxiety during MRI between bore diameters of 60 cm and 70 cm, and to determine the current level of patient anxiety and experience in open scanners in a clinical setrting. Methods: Consecutive patients referred for examination of the spine in 60 cm and 70 cm bores and one open scanner participated. Four established/validated questionnaires, answered before, directly after (N = 155) and one week after (N = 109) the MRI-examination were used, measuring anxiety, fear and depression. Results: No difference was found in the patient scores of anxiety between the 60 cm and the 70 cm scanners on the examination day. At follow-up, patients in the 70 cm bore rated their examination experience better (p &lt; 0.025), compared to patients in the 60 cm bore. Patients in the open scanner rated higher levels of anxiety (p &lt; 0.001) before, directly after and one week after the examination, compared to the closed bore scanners. Conclusion: Scanners with a 70 cm diameter bore seem more tolerable than those with a 60 cm bore. Patients referred to the open scanner had on average a higher tendency to express anxiety. Still, patient anxiety in MRI is challenging and further research required. Implications for practice: Patients prefer to be examined in 70 cm bore scanners compared with 60 cm. If open scanners arent available extended support may be necessary for the most anxious patients. (c) 2019 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

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  • 11. Order onlineBuy this publication >>
    Ahlander, Britt-Marie
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Magnetic Resonance Imaging of the Heart: Image quality, measurement accuracy and patient experience2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Non-invasive diagnostic imaging of atherosclerotic coronary artery disease (CAD) is frequently carried out with cardiovascular magnetic resonance imaging (CMR) or myocardial perfusion single photon emission computed tomography (MPS). CMR is the gold standard for the evaluation of scar after myocardial infarction and MPS the clinical gold standard for ischemia. Magnetic Resonance Imaging (MRI) is at times difficult for patients and may induce anxiety while patient experience of MPS is largely unknown.

    Aims: To evaluate image quality in CMR with respect to the sequences employed, the influence of atrial fibrillation, myocardial perfusion and the impact of patient information. Further, to study patient experience in relation to MRI with the goal of improving the care of these patients.

    Method: Four study designs have been used. In paper I, experimental cross-over, paper (II) experimental controlled clinical trial, paper (III) psychometric crosssectional study and paper (IV) prospective intervention study. A total of 475 patients ≥ 18 years with primarily cardiac problems (I-IV) except for those referred for MRI of the spine (III) were included in the four studies.

    Result: In patients (n=20) with atrial fibrillation, a single shot steady state free precession (SS-SSFP) sequence showed significantly better image quality than the standard segmented inversion recovery fast gradient echo (IR-FGRE) sequence (I). In first-pass perfusion imaging the gradient echo-echo planar imaging sequence (GREEPI) (n=30) had lower signal-to-noise and contrast–to-noise ratios than the steady state free precession sequence (SSFP) (n=30) but displayed a higher correlation with the MPS results, evaluated both qualitatively and quantitatively (II). The MRIAnxiety Questionnaire (MRI-AQ) was validated on patients, referred for MRI of either the spine (n=193) or the heart (n=54). The final instrument had 15 items divided in two factors regarding Anxiety and Relaxation. The instrument was found to have satisfactory psychometric properties (III). Patients who prior CMR viewed an information video scored significantly (lower) better in the factor Relaxation, than those who received standard information. Patients who underwent MPS scored lower on both factors, Anxiety and Relaxation. The extra video information had no effect on CMR image quality (IV).

    Conclusion: Single shot imaging in atrial fibrillation produced images with less artefact than a segmented sequence. In first-pass perfusion imaging, the sequence GRE-EPI was superior to SSFP. A questionnaire depicting anxiety during MRI showed that video information prior to imaging helped patients relax but did not result in an improvement in image quality.

    List of papers
    1. Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols
    Open this publication in new window or tab >>Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols
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    2010 (English)In: CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, ISSN 1475-0961, Vol. 30, no 2, p. 122-129Article in journal (Refereed) Published
    Abstract [en]

    Pandgt;Background: Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction. Methods: Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed. Results: SS_SSFP had significantly better quality scores in all categories (P = 0 center dot 037, P = 0 center dot 014, P = 0 center dot 021, P = 0 center dot 03). SNRinfarct and SNRblood were significantly better for IR_FGRE than for SS_SSFP (P = 0 center dot 048, P = 0 center dot 018). No significant difference was found in SNRmyocardium and CNR. The myocardial volume was significantly larger with SS_SSFP (170 center dot 7 versus 159 center dot 2 ml, P andlt; 0 center dot 001), but no significant difference was found in infarct volume and infarct extent. Conclusion: SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.

    Keywords
    atrial fibrillation, magnetic resonance imaging, myocardial infarction, segmented inversion recovery 2D fast gradient echo, single shot inversion recovery 2D steady-state free precession
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-54159 (URN)10.1111/j.1475-097X.2009.00914.x (DOI)000274438800006 ()
    Available from: 2010-02-26 Created: 2010-02-26 Last updated: 2021-12-28
    2. An echo-planar imaging sequence is superior to a steady-state free precession sequence for visual as well as quantitative assessment of cardiac magnetic resonance stress perfusion
    Open this publication in new window or tab >>An echo-planar imaging sequence is superior to a steady-state free precession sequence for visual as well as quantitative assessment of cardiac magnetic resonance stress perfusion
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    2017 (English)In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 37, no 1, p. 52-61Article in journal (Refereed) Published
    Abstract [en]

    Background To assess myocardial perfusion, steady-state free precession cardiac magnetic resonance (SSFP, CMR) was compared with gradient-echo–echo-planar imaging (GRE-EPI) using myocardial perfusion scintigraphy (MPS) as reference. Methods Cardiac magnetic resonance perfusion was recorded in 30 patients with SSFP and in another 30 patients with GRE-EPI. Timing and extent of inflow delay to the myocardium was visually assessed. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated. Myocardial scar was visualized with a phase-sensitive inversion recovery sequence (PSIR). All scar positive segments were considered pathologic. In MPS, stress and rest images were used as in clinical reporting. The CMR contrast wash-in slope was calculated and compared with the stress score from the MPS examination. CMR scar, CMR perfusion and MPS were assessed separately by one expert for each method who was blinded to other aspects of the study. Results Visual assessment of CMR had a sensitivity for the detection of an abnormal MPS at 78% (SSFP) versus 91% (GRE-EPI) and a specificity of 58% (SSFP) versus 84% (GRE-EPI). Kappa statistics for SSFP and MPS was 0·29, for GRE-EPI and MPS 0·72. The ANOVA of CMR perfusion slopes for all segments versus MPS score (four levels based on MPS) had correlation r = 0·64 (SSFP) and r = 0·96 (GRE-EPI). SNR was for normal segments 35·63 ± 11·80 (SSFP) and 17·98 ± 8·31 (GRE-EPI), while CNR was 28·79 ± 10·43 (SSFP) and 13·06 ± 7·61 (GRE-EPI). Conclusion GRE-EPI displayed higher agreement with the MPS results than SSFP despite significantly lower signal intensity, SNR and CNR.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2017
    Keywords
    cardiac imaging techniques, coronary heart disease, Magnetic Resonance Imaging, nuclear medicine, perfusion
    National Category
    Radiology, Nuclear Medicine and Medical Imaging Medical Laboratory and Measurements Technologies Medical Image Processing Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-130795 (URN)10.1111/cpf.12267 (DOI)000390688200008 ()26147785 (PubMedID)
    Note

    Funding agencies: Medical Research Council of Southeast Sweden [12437]; Futurum, the County council of Jonkoping [12440, 81851, 217261]; Linkoping University; County Council of Ostergotland [281281]; Swedish Heart-Lung Foundation [20120449]

    Available from: 2016-08-24 Created: 2016-08-24 Last updated: 2021-12-28Bibliographically approved
    3. Development and validation of a questionnaire evaluating patient anxiety during Magnetic Resonance Imaging: the Magnetic Resonance Imaging-Anxiety Questionnaire (MRI-AQ)
    Open this publication in new window or tab >>Development and validation of a questionnaire evaluating patient anxiety during Magnetic Resonance Imaging: the Magnetic Resonance Imaging-Anxiety Questionnaire (MRI-AQ)
    Show others...
    2016 (English)In: Journal of Advanced Nursing, ISSN 0309-2402, E-ISSN 1365-2648, Vol. 72, no 6, p. 1368-1380Article in journal (Refereed) Published
    Abstract [en]

    Aim. To develop and validate a new instrument measuring patient anxiety during Magnetic Resonance Imaging examinations, Magnetic Resonance Imaging-Anxiety Questionnaire. Background. Questionnaires measuring patients anxiety during Magnetic Resonance Imaging examinations have been the same as used in a wide range of conditions. To learn about patients experience during examination and to evaluate interventions, a specific questionnaire measuring patient anxiety during Magnetic Resonance Imaging is needed. Design. Psychometric cross-sectional study with test-retest design. Methods. A new questionnaire, Magnetic Resonance Imaging-Anxiety Questionnaire, was designed from patient expressions of anxiety in Magnetic Resonance Imaging-scanners. The sample was recruited between October 2012-October 2014. Factor structure was evaluated with exploratory factor analysis and internal consistency with Cronbachs alpha. Criterion-related validity, known-group validity and test-retest was calculated. Results. Patients referred for Magnetic Resonance Imaging of either the spine or the heart, were invited to participate. The development and validation of Magnetic Resonance Imaging-Anxiety Questionnaire resulted in 15 items consisting of two factors. Cronbachs alpha was found to be high. Magnetic Resonance Imaging-Anxiety Questionnaire correlated higher with instruments measuring anxiety than with depression scales. Known-group validity demonstrated a higher level of anxiety for patients undergoing Magnetic Resonance Imaging scan of the heart than for those examining the spine. Test-retest reliability demonstrated acceptable level for the scale. Conclusion. Magnetic Resonance Imaging-Anxiety Questionnaire bridges a gap among existing questionnaires, making it a simple and useful tool for measuring patient anxiety during Magnetic Resonance Imaging examinations.

    Place, publisher, year, edition, pages
    WILEY-BLACKWELL, 2016
    Keywords
    anxiety; instrument development; magnetic resonance imaging; nurse; nursing; reliability; validity
    National Category
    Other Medical Sciences not elsewhere specified
    Identifiers
    urn:nbn:se:liu:diva-129145 (URN)10.1111/jan.12917 (DOI)000376007400014 ()26893007 (PubMedID)
    Note

    Funding Agencies|Swedish Heart and Lung Foundation; Futurum County Council of Jonkoping

    Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2021-12-28
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    Magnetic Resonance Imaging of the Heart: Image quality, measurement accuracy and patient experience
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  • 12.
    Ahlander, Britt-Marie
    et al.
    Department of Radiology, Ryhov County Hospital, Jönköping.
    Maret, Eva
    Department of Radiology, Ryhov County Hospital, Jönköping / Department of Clinical Physiology, Karolinska University Hospital, Stockholm.
    Brudin, Lars
    Department of Clinical Physiology, Kalmar County Hospital, Kalmar.
    Starck, Sven-Åke
    Department of Natural Science and Biomedicine, School of Health Sciences, Jönköping University / Department of Oncology, Hospital Physics, Ryhov County Hospital, Jönköping.
    Engvall, Jan
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    An echo-planar imaging sequence is superior to a steady-state free precession sequence for visual as well as quantitative assessment of cardiac magnetic resonance stress perfusion2017In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 37, no 1, p. 52-61Article in journal (Refereed)
    Abstract [en]

    Background To assess myocardial perfusion, steady-state free precession cardiac magnetic resonance (SSFP, CMR) was compared with gradient-echo–echo-planar imaging (GRE-EPI) using myocardial perfusion scintigraphy (MPS) as reference. Methods Cardiac magnetic resonance perfusion was recorded in 30 patients with SSFP and in another 30 patients with GRE-EPI. Timing and extent of inflow delay to the myocardium was visually assessed. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated. Myocardial scar was visualized with a phase-sensitive inversion recovery sequence (PSIR). All scar positive segments were considered pathologic. In MPS, stress and rest images were used as in clinical reporting. The CMR contrast wash-in slope was calculated and compared with the stress score from the MPS examination. CMR scar, CMR perfusion and MPS were assessed separately by one expert for each method who was blinded to other aspects of the study. Results Visual assessment of CMR had a sensitivity for the detection of an abnormal MPS at 78% (SSFP) versus 91% (GRE-EPI) and a specificity of 58% (SSFP) versus 84% (GRE-EPI). Kappa statistics for SSFP and MPS was 0·29, for GRE-EPI and MPS 0·72. The ANOVA of CMR perfusion slopes for all segments versus MPS score (four levels based on MPS) had correlation r = 0·64 (SSFP) and r = 0·96 (GRE-EPI). SNR was for normal segments 35·63 ± 11·80 (SSFP) and 17·98 ± 8·31 (GRE-EPI), while CNR was 28·79 ± 10·43 (SSFP) and 13·06 ± 7·61 (GRE-EPI). Conclusion GRE-EPI displayed higher agreement with the MPS results than SSFP despite significantly lower signal intensity, SNR and CNR.

  • 13. Order onlineBuy this publication >>
    Ahle, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Necrotising Enterocolitis: epidemiology and imaging2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Necrotising enterocolitis (NEC) is a potentially devastating intestinal inflammation of multifactorial aetiology in premature or otherwise vulnerable neonates. Because of the broad spectrum of presentations, diagnosis and timing of surgical intervention may be challenging, and imaging needs to be an integrated part of management.

    The first four studies included in this thesis used routinely collected, nationwide register data to describe the incidence of NEC in Sweden 1987‒2009, its variation with time, seasonality, space-time clustering, and associations with maternal, gestational, and perinatal factors, and the risk of intestinal failure in the aftermath of the disease.

    Early infant survival increased dramatically during the study period. The incidence rate of NEC was 0.34 per 1,000 live births, rising from 0.26 per 1,000 live births in the first six years of the study period to 0.57 in the last five. The incidence rates in the lowest birth weights were 100‒160 times those of the entire birth cohort. Seasonal variation was found, as well as space-time clustering in association with delivery hospitals but not with maternal residential municipalities.

    Comparing NEC cases with matched controls, some factors, positively associated with NEC, were isoimmunisation, fetal distress, caesarean section, persistent ductus arteriosus, cardiac and gastrointestinal malformations, and chromosomal abnormalities. Negative associations included maternal pre-eclampsia, maternal urinary infection, and premature rupture of the membranes. Intestinal failure occurred in 6% of NEC cases and 0.4% of controls, with the highest incidence towards the end of the study period.

    The last study investigated current practices and perceptions of imaging in the management of NEC, as reported by involved specialists. There was great consensus on most issues. Areas in need of further study seem mainly related to imaging routines, the use of ultrasound, and indications for surgery.

    Developing alongside the progress of neonatal care, NEC is a complex, multifactorial disease, with shifting patterns of predisposing and precipitating causes, and potentially serious long-term complications. The findings of seasonal variation, spacetime clustering, and negative associations with antenatal exposure to infectious agents, fit into the growing understanding of the central role of bacteria and immunological processes in normal maturation of the intestinal canal as well as in the pathogenesis of NEC. Imaging in the management of NEC may be developed through future studies combining multiple diagnostic parameters in relation to clinical outcome.

    List of papers
    1. Epidemiology and Trends of Necrotizing Enterocolitis in Sweden: 1987-2009
    Open this publication in new window or tab >>Epidemiology and Trends of Necrotizing Enterocolitis in Sweden: 1987-2009
    2013 (English)In: Pediatrics, ISSN 0031-4005, E-ISSN 1098-4275, Vol. 132, no 2, p. E443-E451Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: To investigate temporal, seasonal, and geographic variations in the incidence of necrotizing enterocolitis (NEC) and its relation to early infant survival in the Swedish population and in subgroups based on gestational age, birth weight, and gender. less thanbrgreater than less thanbrgreater thanMETHODS: In the Swedish birth cohort of 1987 through 2009 all children with a diagnosis of NEC were identified in the National Patient Register, the Swedish Medical Birth Register, and the National Cause of Death Register. NEC incidence, early mortality, and seasonality were analyzed with descriptive statistics, Poisson regression, and auto regression. less thanbrgreater than less thanbrgreater thanRESULTS: The overall incidence of NEC was 3.4 in 10 000 live births, higher in boys than in girls (incidence rate ratio 1.22, 95% confidence interval 1.06-1.40, P = .005), with a peak in November and a trough in May, and increased with an average of similar to 5% a year during the study period. In most subgroups, except the most immature, an initial decrease was followed by a steady increase. Seven-day mortality decreased strongly in all subgroups over the entire study period (annual incidence rate ratio 0.96, 95% confidence interval 0.95-0.96, P andlt; .001). This was especially marked in the most premature and low birth weight infants. less thanbrgreater than less thanbrgreater thanCONCLUSIONS: After an initial decrease, the incidence of NEC has increased in Sweden during the last decades. An association with the concurrent dramatically improved early survival seems likely.

    Place, publisher, year, edition, pages
    American Academy of Pediatrics, 2013
    Keywords
    necrotizing enterocolitis, premature infants, perinatal mortality, perinatal care, epidemiology, trends, seasonal variation
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-98148 (URN)10.1542/peds.2012-3847 (DOI)000322957300017 ()
    Note

    Funding Agencies|County Council of Ostergotland||Futurum||Academy of Health Care||Jonkoping County Council, Jonkoping, Sweden||Medical Research Council of Southeast Sweden||

    Available from: 2013-09-30 Created: 2013-09-30 Last updated: 2018-03-27
    2. Population-based study showed that necrotising enterocolitis occurred in space-time clusters with a decreasing secular trend in Sweden
    Open this publication in new window or tab >>Population-based study showed that necrotising enterocolitis occurred in space-time clusters with a decreasing secular trend in Sweden
    Show others...
    2017 (English)In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 106, no 7, p. 1097-1102Article in journal (Refereed) Published
    Abstract [en]

    Aim: This study investigated space-time clustering of neonatal necrotising enterocolitis over three decades. Methods: Space-time clustering analyses objects that are grouped by a specific place and time. The Knox test and Kulldorffs scan statistic were used to analyse space-time clusters in 808 children diagnosed with necrotising enterocolitis in a national cohort of 2 389 681 children born between 1987 and 2009 in Sweden. The municipality the mother lived in and the delivery hospital defined closeness in space and the time between when the cases were born - seven, 14 and 21 days - defined closeness in time. Results: The Knox test showed no indication of space-time clustering at the residential level, but clear indications at the hospital level in all the time windows: seven days (p = 0.026), 14 days (p = 0.010) and 21 days (p = 0.004). Significant clustering at the hospital level was found during 1987-1997, but not during 1998-2009. Kulldorffs scan statistic found seven significant clusters at the hospital level. Conclusion: Space-time clustering was found at the hospital but not residential level, suggesting a contagious environmental effect after delivery, but not in the prenatal period. The decrease in clustering over time may reflect improved routines to minimise the risk of contagion between patients receiving neonatal care.

    Place, publisher, year, edition, pages
    WILEY, 2017
    Keywords
    Cluster analysis; Necrotising enterocolitis; Neonatal care; Precipitating contagion; Preterm infant
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-139608 (URN)10.1111/apa.13851 (DOI)000405216700022 ()28349558 (PubMedID)
    Note

    Funding Agencies|Swedish government; county councils

    Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2022-10-04
    3. Maternal, fetal and perinatal factors associated with necrotizing enterocolitis in Sweden: A national case-control study
    Open this publication in new window or tab >>Maternal, fetal and perinatal factors associated with necrotizing enterocolitis in Sweden: A national case-control study
    2018 (English)In: PLOS ONE, E-ISSN 1932-6203, PLoS ONE, ISSN 1932-6203, Vol. 13, no 3, article id e0194352Article in journal (Refereed) Published
    Abstract [en]

    Objective

    To analyze associations of maternal, fetal, gestational, and perinatal factors with necrotizing enterocolitis in a matched case-control study based on routinely collected, nationwide register data.

    Study design

    All infants born in 1987 through 2009 with a diagnosis of necrotizing enterocolitis in any of the Swedish national health care registers were identified. For each case up to 6 controls, matched for birth year and gestational age, were selected. The resulting study population consisted of 720 cases and 3,567 controls. Information on socioeconomic data about the mother, maternal morbidity, pregnancy related diagnoses, perinatal diagnoses of the infant, and procedures in the perinatal period, was obtained for all cases and controls and analyzed with univariable and multivariable logistic regressions for the whole study population as well as for subgroups according to gestational age.

    Results

    In the study population as a whole, we found independent positive associations with necrotizing enterocolitis for isoimmunization, fetal distress, cesarean section, neonatal bacterial infection including sepsis, erythrocyte transfusion, persistent ductus arteriosus, cardiac malformation, gastrointestinal malformation, and chromosomal abnormality. Negative associations were found for maternal weight, preeclampsia, maternal urinary infection, premature rupture of the membranes, and birthweight. Different patterns of associations were seen in the subgroups of different gestational age.

    Conclusion

    With some interesting exceptions, especially in negative associations, the results of this large, population based study, are in keeping with earlier studies. Although restrained by the limitations of register data, the findings mirror conceivable pathophysiological processes and underline that NEC is a multifactorial disease.

    Place, publisher, year, edition, pages
    San Francisco, United States: Public Library of Science, 2018
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-146093 (URN)10.1371/journal.pone.0194352 (DOI)000428168400016 ()29570713 (PubMedID)2-s2.0-85044427061 (Scopus ID)
    Note

    Funding agencies: Region Ostergotland, Sweden [LiO-107641]; Medical Research Council of Southeast Sweden [FORSS-77481]; Futurum - the Academy of Health Care, Jonkoping County Council, Jonkoping, Sweden; Region Ostergotland [LIO-130291, LIO-204581, LIO-280451, LIO-361481, L

    Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2021-06-14Bibliographically approved
    4. The role of imaging in the management of necrotising enterocolitis: a multispecialist survey and a review of the literature
    Open this publication in new window or tab >>The role of imaging in the management of necrotising enterocolitis: a multispecialist survey and a review of the literature
    2018 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 28, no 9, p. 3621-3631Article in journal (Refereed) Published
    Abstract [en]

    Objectives

    To investigate current practices and perceptions of imaging in necrotising enterocolitis (NEC) according to involved specialists, put them in the context of current literature, and identify needs for further investigation.

    Methods

    Two hundred two neonatologists, paediatric surgeons, and radiologists answered a web-based questionnaire about imaging in NEC at their hospitals. The results were descriptively analysed, using proportion estimates with 95% confidence intervals.

    Results

    There was over 90% agreement on the value of imaging for confirmation of the diagnosis, surveillance, and guidance in decisions on surgery as well as on abdominal radiography as the first-choice modality and the most important radiographic signs. More variation was observed regarding some indications for surgery and the use of some ultrasonographic signs. Fifty-eight per cent stated that ultrasound was used for NEC at their hospital. Examination frequency, often once daily or more but with considerable variations, and projections used in AR were usually decided individually rather than according to fixed schedules. Predicting the need of surgery was regarded more important than formal staging.

    Conclusion

    Despite great agreement on the purposes of imaging in NEC and the most important radiographic signs of the disease, there was considerable diversity in routines, especially regarding examination frequency and the use of ultrasound. Apart from continuing validation of ultrasound, important objectives for future studies include definition of the supplementary roles of both imaging modalities in relation to other diagnostic parameters and evaluation of various imaging routines in relation to timing of surgery, complications, and mortality rate.

    Place, publisher, year, edition, pages
    Springer, 2018
    Keywords
    Enterocolitis, necrotising, Abdominal radiography, Ultrasonography, Surveys and questionnaires, Professional practice
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-146094 (URN)10.1007/s00330-018-5362-x (DOI)000440984300006 ()
    Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-08-24
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    Necrotising Enterocolitis: epidemiology and imaging
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  • 14.
    Ahle, Margareta
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Rubesova, Erika
    Stanford university, US.
    Ringertz, Hans
    Stanford university, US.
    The significance of radiographic and ultrasonographic findings in the management of necrotising enterocolitis - results from a survey2017Conference paper (Other academic)
    Abstract [en]

    Necrotising Enterocolitis (NEC) remains a potentially devastating emergency in neonates, predominantly the premature. Ever since it was first described in the 60's, imaging has played a great role in definition, staging, and monitoring of the disease. The radiographic image can change before the clinical condition, but typical signs are often transient and may be missing even in severe NEC [1-4]. These circumstances have led to the recommendation of frequent imaging and to the insight that the clinical decisions cannot rely solely on radiological signs [5-7]. Ultrasound (US) as a possibility to enhance sensitivity and diagnostic accuracy was first described in the mid 80's [8, 9] and was included in a diagnostic algorithm suggested by in 1994 [6], but despite great effort to develop and validate the method, its role in the management of NEC has not yet been established [7, 10, 11].

    Meanwhile, in order to improve interobserver agreement and diagnostic accuracy of AR, the radiographic signs of NEC have also been systematized into the DAAS scale [12]. Imaging, as an adjunct to clinical assessment [11], is crucial in the diagnosis and management of NEC. The purpose of this survey was to investigate current views and routines, as described by involved specialists, and identify areas in need of further study and discussion.

    Download full text (pdf)
    The significance of radiographic and ultrasonographic findings in the management of necrotising enterocolitis - results from a survey
  • 15.
    Ahle, Margareta
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Rubesova, Erika
    Stanford university, US.
    Ringertz, Hans
    Stanford university, US.
    The use of imaging in necrotising enterocolitis - results from a survey2017Conference paper (Other academic)
    Download full text (pdf)
    E-poster C-2872
  • 16.
    Ahmad, Awais
    et al.
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Dahle, Charlotte
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Rönnelid, Johan
    Uppsala Univ, Sweden.
    Sjöwall, Christopher
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Medicine Center, Department of Rheumatology.
    Kechagias, Stergios
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Mag- tarmmedicinska kliniken.
    Autoantibodies Associated with Autoimmune Liver Diseases in a Healthy Population: Evaluation of a Commercial Immunoblot Test2022In: Diagnostics, ISSN 2075-4418, Vol. 12, no 7, article id 1572Article in journal (Refereed)
    Abstract [en]

    Autoantibodies constitute important tools for diagnosing the autoimmune liver diseases (AILD) autoimmune hepatitis and primary biliary cholangitis. The EUROLINE immunoblot assay, detecting multiple specificities, is widely used, but the clinical importance of weakly positive findings is unclear. The manufacturers recommended cut-off was evaluated by investigating AILD-associated autoantibodies in 825 blood donors and 60 confirmed AILD cases. Positive findings were followed up with immunofluorescence microscopy on rat tissue, anti-M2-ELISA, alternative immunoblot assay, and liver function tests. Thirty-six (4.4%) blood donors were positive with EUROLINE. The most common specificities were LC-1 (1.6%), gp210 (1.3%), and AMA-M2 (1.1%). In general, the positive results were higher in patients than in blood donors, whereas anti-LC-1 was higher in blood donors. The liver function tests were slightly elevated in 2 of the 36 immunoblot positive blood donors. The majority of the positive EUROLINE findings could not be confirmed with the follow-up tests. The EUROLINE-Autoimmune Liver Diseases-(IgG) immunoblot detected autoantibodies in 4.4% of blood donors without signs of AILD. Our findings indicate that the recommended cut-off can be raised for most specificities without loss of diagnostic sensitivity. The prevalence of anti-LC-1 among blood donors indicates a problem with the antigen source.

    Download full text (pdf)
    fulltext
  • 17.
    Ahnesjö, Anders
    et al.
    Uppsala University, Sweden.
    van Veelen, Bob
    Elekta Brachytherapy, Netherlands.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Karolinska University Hospital, Sweden.
    Collapsed cone dose calculations for heterogeneous tissues in brachytherapy using primary and scatter separation source data2017In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 139, p. 17-29Article in journal (Refereed)
    Abstract [en]

    Background and Objective: Brachytherapy is a form of radiation therapy using sealed radiation sources inserted within or in the vicinity of the tumor of, e.g., gynecological, prostate or head and neck cancers. Accurate dose calculation is a crucial part of the treatment planning. Several reviews have called for clinical software with model-based algorithms that better take into account the effects of patient individual distribution of tissues, source-channel and shielding attenuation than the commonly employed TG-43 formalism which simply map homogeneous water dose distributions onto the patient. In this paper we give a comprehensive and thorough derivation of such an algorithm based on collapsed cone point-kernel superposition, and describe details of its implementation into a commercial treatment planning system for clinical use. Methods: A brachytherapy version of the collapsed-cone algorithm using analytical raytraces of the primary photon radiation followed by successive scattering dose calculation for once and multiply scattered photons is described in detail, including derivation of the corresponding set of recursive equations for energy transport along cone axes/transport lines and the coupling to clinical source modeling. Specific implementation issues for setting up of the calculation grid, handling of intravoxel gradients and voxels partly containing non patient applicator material are given. Results: Sample runs for two clinical cases are shown, one being a gynecological application with a tungsten-shielded applicator and one a breast implant. These two cases demonstrate the impact of improved dose calculation versus TG-43 formalism. Conclusions: Use of model-based dose calculation algorithms for brachytherapy taking the three-dimensional treatment geometry into account increases the dosimetric accuracy in planning and follow up of treatments. The comprehensive description and derivations provided gives a rigid background for further clinical, educational and research applications. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

  • 18.
    Alevronta, Eleftheria
    et al.
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden / Department of Oncology-Pathology, Division of Medical Radiation Physics, Karolinska Institutet, Sweden.
    Lind, Helena
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden.
    Al-Abany, Massoud
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden / Department of Hospital Physics, Karolinska University Hospital, Stockholm, Sweden.
    Waldenström, Ann-Charlotte
    Department of Oncology, Clinical Cancer Epidemiology, the Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden / Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Olsson, Caroline
    Department of Radiation Physics, the Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden / Department of Oncology, Clinical Cancer Epidemiology, the Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
    Dunberger, Gail
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden.
    Mavroidis, Panayotis
    Department of Oncology-Pathology, Division of Medical Radiation Physics, Karolinska Institutet, Sweden / Department of Medical Physics, Larissa University Hospital, Larissa, Greece.
    Nyberg, Tommy
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden.
    Johansson, Karl-Axel
    Department of Radiation Physics, the Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
    Åvall-Lundqvist, Elisabeth
    Department of Gynecologic Oncology, Karolinska University Hospital, Stockholm, Sweden.
    Steineck, Gunnar
    Department of Oncology-Pathology, Division of Clinical Cancer Epidemiology, Karolinska Institutet, Stockholm, Sweden / Department of Oncology, Clinical Cancer Epidemiology, the Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
    Lind, Bengt K
    Department of Oncology-Pathology, Division of Medical Radiation Physics, Karolinska Institutet, Sweden.
    Dose-response relationships for an atomized symptom of fecal incontinence after gynecological radiotherapy.2013In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 52, no 4, p. 719-26Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The aim of this study was to investigate what bowel organ and delivered dose levels are most relevant for the development of 'emptying of all stools into clothing without forewarning' so that the related dose-responses could be derived as an aid in avoiding this distressing symptom in the future.

    MATERIAL AND METHODS: Of the 77 gynecological cancer survivors treated with radiotherapy (RT) for gynecological cancer, 13 developed the symptom. The survivors were treated between 1991 and 2003. The anal-sphincter region, the rectum, the sigmoid and the small intestines were all delineated and the dose-volume histograms were exported for each patient. The dose-volume parameters were estimated fitting the data to the Relative Seriality (RS), the Lyman and the generalized Equivalent Uniform Dose (gEUD) model.

    RESULTS: The dose-response parameters for all three models and four organs at risk (OARs) were estimated. The data from the sigmoid fits the studied models best: D50 was 58.8 and 59.5 Gy (RS, Lyman), γ50 was 1.60 and 1.57 (RS, Lyman), s was 0.32, n was 0.13 and a was 7.7 (RS, Lyman, gEUD). The estimated volume parameters indicate that the investigated OARs behave serially for this endpoint. Our results for the three models studied indicate that they have the same predictive power (similar LL values) for the symptom as a function of the dose for all investigated OARs.

    CONCLUSIONS: In our study, the anal-sphincter region and sigmoid fit our data best, but all OARs were found to have steep dose-responses for 'emptying of all stools into clothing without forewarning' and thus, the outcome can be predicted with an NTCP model. In addition, the dose to the four studied OARs may be considered when minimizing the risk of the symptom.

  • 19.
    Alevronta, Eleftheria
    et al.
    Karolinska Institute, Sweden; Sahlgrens Acad, Sweden.
    Åvall Lundqvist, Elisabeth
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology. Karolinska Institute, Sweden.
    al-Abany, Massoud
    Karolinska Institute, Sweden; Karolinska University Hospital, Sweden.
    Nyberg, Tommy
    Karolinska Institute, Sweden.
    Lind, Helena
    Karolinska Institute, Sweden.
    Waldenstrom, Ann-Charlotte
    Sahlgrens Acad, Sweden; Sahlgrens University Hospital, Sweden.
    Olsson, Caroline
    Sahlgrens Acad, Sweden; Gothenburg University, Sweden.
    Dunberger, Gail
    Karolinska Institute, Sweden; Ersta Skondal University of Coll, Sweden.
    Bergmark, Karin
    Karolinska Institute, Sweden; Sahlgrens Acad, Sweden; Sahlgrens University Hospital, Sweden.
    Steineck, Gunnar
    Karolinska Institute, Sweden; Sahlgrens Acad, Sweden.
    Lind, Bengt K.
    Karolinska Institute, Sweden.
    Time-dependent dose-response relation for absence of vaginal elasticity after gynecological radiation therapy2016In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 120, no 3, p. 537-541Article in journal (Refereed)
    Abstract [en]

    Background and purpose: To investigate the dose-response relation between the dose to the vagina and the patient-reported symptom absence of vaginal elasticity and how time to follow-up influences this relation. Material and methods: The study included 78 long-term gynecological cancer survivors treated between 1991 and 2003 with external beam radiation therapy. Of those, 24 experienced absence of vaginal elasticity. A normal tissue complication model is introduced that takes into account the influence of time to follow-up on the dose-response relation and the patients age. The best estimates of the dose-response parameters were calculated using Probit, Probit-Relative Seriality (RS) and Probit-time models. Log likelihood (LL) values and the Akaike Information Criterion (AIC) were used to evaluate the model fit. Results: The dose-response parameters for absence of vaginal elasticity according to the Probit and Probit-time models with the 68% Confidence Intervals (CI) were: LL = 39.8, D-50 = 49.7 (47.2-52.4) Gy, gamma(50) =1.40 (1.12-1.70) and LL = 37.4, D-50 = 46.9 (43.5-50.9) Gy, gamma(50) = 1.81 (1.17-2.51) respectively. Conclusions: The proposed model, which describes the influence of time to follow-up on the dose response relation, fits our data best. Our data indicate that the steepness of the dose-response curve of the dose to the vagina and the symptom absence of vaginal elasticity increases with time to follow-up, while D-50 decreases. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

  • 20.
    Ali, Adnan
    et al.
    Univ Lancaster, England.
    Ahle, Margareta
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Department of Health, Medicine and Caring Sciences.
    Björnsson, Bergthor
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Sandström, Per
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Portal vein embolization with N-butyl cyanoacrylate glue is superior to other materials: a systematic review and meta-analysis2021In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 31, no 8, p. 5464-5478Article, review/survey (Refereed)
    Abstract [en]

    Objectives It remains uncertain which embolization material is best for portal vein embolization (PVE). We investigated the various materials for effectiveness in inducing future liver remnant (FLR) hypertrophy, technical and growth success rates, and complication and resection rates. Methods A systematic review from 1998 to 2019 on embolization materials for PVE was performed on Pubmed, Embase, and Cochrane. FLR growth between the two most commonly used materials was compared in a random effects meta-analysis. In a separate analysis using local data (n = 52), n-butyl cyanoacrylate (NBCA) was compared with microparticles regarding costs, radiation dose, and procedure time. Results In total, 2896 patients, 61.0 +/- 4.0 years of age and 65% male, from 51 papers were included in the analysis. In 61% of the patients, either NBCA or microparticles were used for embolization. The remaining were treated with ethanol, gelfoam, or sclerosing agents. The FLR growth with NBCA was 49.1% +/- 29.7 compared to 42.2% +/- 40 with microparticles (p = 0.037). The growth success rate with NBCA vs microparticles was 95.3% vs 90.7% respectively (p &lt; 0.001). There were no differences in major complications between NBCA and microparticles. In the local analysis, NBCA (n = 41) entailed shorter procedure time and reduced fluoroscopy time (p &lt; 0.001), lower radiation exposure (p &lt; 0.01), and lower material costs (p &lt; 0.0001) than microparticles (n = 11). Conclusion PVE with NBCA seems to be the best choice when combining growth of the FLR, procedure time, radiation exposure, and costs.

  • 21.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Absorbed dose equations: The general solution of the absorbed dose equation and solutions under different kinds of radiation equilibrium1978Report (Other academic)
    Abstract [sv]

    This report is a logical continuation of two papers concerning basic concepts in dosimetry. The first paper (1) is u critical analysis of the concepts of ionizing radiation and energy imparted as defined by the ICRU (2). The second paper (3) gives a definition of the energy imparted, the fundamental quantity in radiation dosimetry, which is equivalent to that given by the ICRU but which has a different form. This alternative definition of the energy imparted is suitable in deriving a general expression, in terms of particle fluences and interaction cross sections, for the absorbed dose valid also in situations where no kind of radiation equilibrium is established. It is, however, today not possible to quantify this expression for the absorbed dose. All practical calculations of absorbed dose rely on the assumption of one or another type of radiation equilibrium. The aim of this work is to analyze different kinds of radiation equilibrium conditions and to find the corresponding exact expressions for the absorbed dose. The concept of radiation equilibrium is more carefully analyzed than has been done previously (4, 5, 6). Moreover, the definition of the mass energy absorption coefficient for indirectly (uncharged) ionizing particles is critically analyzed. A new definition is proposed relevant to calculations of the absorbed dose in cases when charged particle equilibrium exists within a homogeneous medium due to the uniform liberation of charged particles, by uncharged particles.

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    Absorbed dose equations : The general solution of the absorbed dose equation and solutions under different kinds of radiation equilibrium
  • 22.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Bragg-Gray Dosimetry: Theory of Burch2001Report (Other academic)
    Abstract [en]

    The theoretical approach to Bragg-Gray dosimetry is: a Bragg-Gray cavity is a cavity (detector) so small that, when inserted into a medium, it does not disturb the fluence of charged particles existing in the medium.

    This means that the ideal Bragg-Gray cavity (detector) is one of infinitesimal dimensions, a "point" detector. In practice, such detectors do not exist but many real detectors may, in a first approximation, be treated as Bragg-Gray detectors to a high degree of accuracy. Corrections needed (so called perturbation corrections) to account for the deviation of the signal from a practical detector from that of an ideal one has been treated by, e.g., ICRU 1984, Alm Carlsson, 1985, Svensson and Brahme 1986, Alm Carlsson 1987.

    Derivation of "perturbation corrections" needs careful consideration and under-standing of the ideal case, i.e., that from which deviations are to be corrected for. The ideal case of a Bragg-Gray detector has been treated by Bragg 1912, Gray 1936, Laurence 1937, Spencer and Attix 1955 and Burch 1955.

    The formulation of Bragg-Gray theory by Spencer and Attix has found wide practical application and has been treated in detail elsewhere. The theory of Burch treats the same problem as did Spencer and Attix, viz., the significance of generation and slowing down of delta-particles in both medium and detector. Burch treated the problem in considerable detail but didn't find a solution for practical calculations. From a physical point of view, however, there is much to learn from Burch's approach. Also, his treatment of so called track ends, evaluated in some detail by Burch 1957, has been adapted in later versions of the Spencer-Attix formulation of Bragg-Gray theory.

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    Bragg-Gray Dosimetry : Theory of Burch
  • 23.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Burlins kavitetsteori1979Report (Other academic)
    Abstract [sv]

    Burlins kavitetsteori är en generell teori i den meningen att inga krav finns på detektorns dimensioner jämfört med sekundärelektronernas räckvidder. Detektorn måste dock vara "tunn" för fotonerna dvs inte ge någon nämnvärd attenuering av de mot detektorn infallande fotonerna

     

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    Burlins kavitetsteori
  • 24.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Effective use of Monte Carlo methods for simulating photon transport with special reference to slab penetration problems in X-raydiagnostics1981Report (Other academic)
    Abstract [sv]

    The analys is of Monte Carlo methods here has been made in connection with a particular problem concerning the transport of low energy photons (30-140 keV) through layers of water with thicknesses between 5 and 20 cm.

    While not claiming to be a complete exposition of available Monte Carlo techniques, the methodological analyses are not restricted to this particular problem. The report describes in a general manner a number of methods which can be used in order to obtain results of greater precision in a fixed computing time.

    Monte Carlo methods have been used for many years in reactor technology, particularly for solving problems associated with neutron transport, but also for studying photon transport through radiation shields. In connection with these particular problems, mathematically and statistically advanced methods have been worked out. The book by Spanier and Gelbard (1969) is a good illustration of this.

    In the present case, a more physical approach to Monte Carlo methods for solving photon transport problems is made (along the lines employed by Fano, Spencer and Berger (1959)) with the aim of encouraging even radiation physicists to use more sophisticated Monte Carlo methods. Today, radiation physicists perform Monte Carlo calculations with considerable physical significance but often with unnecessarily straightforward methods.

    As Monte Carlo calculations can be predicted to be of increasing importance in tackling problems in radiation physics, e.g., in X-ray diagnostics, it is worthwhile to study the Monte Carlo approach for its own sake.

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    Effective use of Monte Carlo methods for simulating photon transport with special reference to slab penetration problems in X-raydiagnostics
  • 25.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Fanos Teorem2002Report (Other academic)
    Abstract [sv]

    I ett oändligt medium erhålles en fullt uppbyggd fluens i alla punkter av mediet. I ett ändligt medium erhålles inte full uppbyggnad av fluensen på avstånd mindre än en maximal "partikelräckvidd" från begränsningsytorna. Fanos teorem har visats gälla för alla punkter i ett oändligt medium men kan endast gälla i det inre av ett ändligt medium där förhållandena är ekvivalenta med dem i det oändliga mediet.

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    Fanos Teorem
  • 26.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Fotonspridningsprocessen vid röntgendiagnostiska strålkvaliteter1981Report (Other academic)
    Abstract [sv]

    Spridd strålning utgör ett allvarligt problem inom röntgendiagnostiken. Kunskap om den spridda strålningen, dess uppträdande i patient och detektor, är en förutsättning för att finna effektiva metoder att reducera den och begränsa dess negativa inverkan på bildkvaliten. Denna kunskap kan vinnas genom transportberäkningar, t ex Monte Carlo simulering (ALM CARLSSON). Detaljerad kännedom om tvärsnitten för inkoherent och koherent spridning är därvid av stor betydelse. Vid utnyttjandet av datortomografi för bestämning av elektrontäthet eller benmineralhalt och annan s.k. tomokemi krävs också välbestämda totala attenueringstvärsnitt, varav Compton och koherent spridning utgör en icke försumbar andel av attenueringen i energiområdet 10-100 keV.

    Fotonspridningen kan också utnyttjas positivt för att ge information om den kropp i vilken spridningen ägt rum. En review över metoder att använda Comptonspridningen till att göra elektrontäthetsbestämningar, såväl i enskilda volymer som i tomografiska snitt har publicerats av CARLSSON och ALM CARLSSON (1979).

    En viktig applikation av Comptonspridningen (inkoherent spridning) i diagnostisk radiologi är metoden att ur mätningar av antalet och energifördelningen av de fotoner, som spridits en viss vinkel bestämma energispektret av den primära röntgenstrålningen. Även här är kännedom om spridningstvärsnitten av vital betydelse för noggrannheten i bestämningen.

    Jag skall här ge en redogörelse för vår aktuella kunskap om tvärsnitten för koherent och inkoherent spridning för fotoner av röntgendiagnostisk kvalitet (10-200 keV). För dessa är det inte tillräckligt att applicera Klein-Nishina tvärsnittet, som gäller för spridning mot fria elektroner i vila utan hänsyn måste tas till att de atomära elektronerna är bundna och i rörelse i kollisionsögonblicket. Speciellt kommer konsekvenserna för metoden att bestämma primärstrålningsspektrum ur uppmätta spektra av spridd strålning att belysas.

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    Fotonspridningsprocessen vid röntgendiagnostiska strålkvaliteter
  • 27.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Kavitetsteori: allmänna grunder1981Report (Other academic)
    Abstract [sv]

    Kavitetsteori är av fundamental betydelse för dosimetrin. Dess uppgift är att relatera den absorberade dosen i en dosimeter till den absorberade dosen i en given punkt i det medium dosimetern är placerad. Idealt har dosimetern samma strålningsabsorberande egenskaper som mediet. Detta är emellertid nästan aldrig möjligt att uppnå.

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    Kavitetsteori : allmänna grunder
  • 28.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Klassisk elektrodynamik: Växelverkan mellan laddade partiklar och elektromagnetiska fält1975Report (Other academic)
    Abstract [sv]

    Varifrån kommer det elektromagnetiska fältet? Elektromagnetiska fält genereras av laddningar i rörelse (en laddning i vila genererar ett elektrostatiskt fält). I definitionen av fältstorheterna ovan tänks i första hand att det elektromagnetiska fält i vilket den betraktade laddningen q rör sig härstammar från alla de övriga laddningarna och deras rörelser i rymden. (Laddningen q genererar även själv ett elektromagnetiskt fält, som under vissa omständigheter återverkar på dess egen rörelse. Denna effekt diskuteras i ett senare avsnitt).

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    Klassisk elektrodynamik : Växelverkan mellan laddade partiklar och elektromagnetiska fält
  • 29.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Kvantelektrodynamik för elektroner: Feynmandiagram och strålningskorrektioner av tvärsnitt1975Report (Other academic)
    Abstract [sv]

    Utvecklingen av kvantelektrodynamiken startade strax efter det att den icke-relativistiska kvantmekaniken fullbordats och innebär en kombination av kvantmekaniska principer och klassisk elektrodynamik. Upphovsmän till kvantelektrodynamiken var Dirac, Heisenberg och Pauli. Diracs relativistiska, kvantmekaniska teori för elektroner ledde till den så kallade hålteorin för och förutsägelsen av en positivt laddad elektron = positronen. Väsentliga insatser inom kvantelektrodynamiken har gjorts av R.P. Feynman från vilken de så kallade Feynmandiagrammen härstammar. Genom en omtolkning av lösningarna till Diracs relativistiska, kvantmekaniska ekvation för elektronerna ersättes hålteorin för positroner med en beskrivning enligt vilken positronen representeras av vågor, som går bakåt i tiden. Denna tolkning av positronen möjliggör väsentliga förenklingar i beräkningen av tvärsnitt för växelverkansprocesser mellan elektroner och elektromagnetiska fält -förenklingar, som blir speciellt betydelsefulla vid behandlingen av mer komplicerade växelverkansprocesser inkluderande de så kallade strålningskorrektionerna till de enklare processerna. Feynmandiagram över även enklare växelverkansprocesser börjar dyka upp i moderna läroböcker (t ex Roy & Reed: "Interactions of photons and leptons with matter". Academic Press 1968) liksom tabellverk som ger strålningskorrektioner till olika elektrodynamiska växelverkansprocesser, (t ex Hubbell: "Photon cross sections, attenuation coefficients, and energy absorption coefficients from 10 keV to 100 GeV. NSRDS-NBS 29 (1969)). I det följande göres ett försök att kvalitativt redogöra för innebörden av Feynmandiagrammen och strålningskorrektionerna. (Analoga diagram kan användas vid beskrivningen av växelverkansprocesserna mellan nukleoner och mesonfält. För dessa redogöres dock inte här).

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    Kvantelektrodynamik för elektroner : Feynmandiagram och strålningskorrektioner av tvärsnitt
  • 30.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Kärnfysikaliska grunder för radioaktiva nuklider1974Report (Other academic)
    Abstract [sv]

    Förståelsen av den joniserande strålningen och dess växelverkan med materia förutsätter kännedom om atomens natur. Atomen (grekiska "atomos" = odelbar) är den minsta del av ett grundämne, som bibehåller ämnets identitet, dvs. uppvisar dess karakteristiska kemiska egenskaper. Individuella atomer är för små för att direkt kunna observeras. Man kan däremot observera vissa egenskaper hos atomen. Med hjälp av dessa försöker man bygga upp en enkel och åskådlig bild av atomen, en atommodell, med vars hjälp man kan förklara experimentellt gjorda observationer.

    Atomen består av en central, elektriskt positivt laddad kärna, till vilken den största delen av atomens massa är koncentrerad. Runt kärnan kretsar elektriskt negativt laddade elektroner, vilka neutraliserar kärnans positiva laddning, så att atomen utåt verkar elektriskt neutral.

    Atomkärnan är uppbyggd av två sorters elementarpartiklar, protoner och neutroner. En proton och en neutron har ungefär samma massa, men medan protonen är bärare av en positiv laddning lika stor som elektronens negativa laddning är neutronen elektriskt neutral. En elektriskt neutral atom innehåller alltså lika många protoner i kärnan som elektroner i det omgivande elektronskalet. Ett gemensamt namn på protoner och neutroner är nukleon.

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    Kärnfysikaliska grunder för radioaktiva nuklider
  • 31.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Skalära och vektoriella fysikaliska storheter: Deras betydelse för förståelsen av röntgendetektorernas uppträdande i ett strålningsfält1981Report (Other academic)
    Abstract [sv]

    Joniserande strålning är ett fysikaliskt fenomen. Varje del av rymden där detta fenomen uppträder utgör ett strålningsfält. För att kunna ge ett mått på "mängden strålning" i fältet krävs att vi först definierar en storhet och därefter mäter eller beräknar storleken på denna uttryckt i antalet enheter av storheten i fråga. Det förekommer alltför ofta att man talar om att "mäta strålningen", vilket egentligen är en omöjlighet. Om man t.ex. anger att ett visst raster "reducerar den spridda strålningen med en faktor 2" så säger detta ingenting om man inte samtidigt anger vilken storhet man avser; fluensen, energifluensen, antalet fotoner som träffar en detektor, summaenergin hos fotonerna som träffar detektorn eller energin absorberad (energy imparted) i detektorn.

    Signalen från en detektor, som placeras i strålningsfältet beror i första hand av den i detektorn absorberade strålningsenergin även om modifikationer till följd av den aktuella fördelningen i tid och rum kan förekomma. Förståelsen aven detektors uppträdande i strålningsfältet är i första hand av dosimetrisk natur.

    Vi skall här närmare betrakta de storheter, som används för att beskriva strålningsfältet och hur dessa kan användas för att bestämma väntevärdet av den i en strålningsdetektor absorberade strålningsenergin. Samtidigt ges tillfälle att presentera de nya storheter och den nya terminologi, som infördes i senaste ICRU-rapporten över kvantiteter och enheter.

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    Skalära och vektoriella fysikaliska storheter : Deras betydelse för förståelsen av röntgendetektorernas uppträdande i ett strålningsfält
  • 32.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Spencer-Attix Cavity Theory2002Report (Other academic)
    Abstract [en]

    The cavity theory by Spencer and Attix treats the energy deposition in a Bragg-Gray (B-G) cavity (detector). Originally the theory was developed for the case of a B-G detector inside a medium irradiated with photons and assuming electronic equilibrium in the medium at the position of the cavity. The theory is also applicable in media irradiated with other types of uncharged ionizing particles (e.g., neutrons) and charged particles such as electrons and protons.

    The special case of photon irradiation under CPE (charged particle equilibrium) conditions was coupled to a model for calculating the energy spectrum of the equilibrium fluence of electrons in the undisturbed medium. For other situations, e.g., in a medium externally irradiated with electrons, the problem is to evaluate the energy spectrum of the electron fluence at the point considered in the medium. Today, this is mostly accomplished using Monte Carlo simulations.

    A Bragg-Gray cavity is regarded to be so small that:

    • the energy imparted to the cavity from electrons released by photons in the cavity is negligible compared to the energy imparted from electrons released by photons in the surrounding medium and passing through the cavity
    • the cavity should not disturb the fluence of electrons in the medium, i. e., the fluence of electrons traversing the cavity is assumed to be identical to that existing at the point of interest in the medium in the absence of the cavity.
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    Spencer-Attix Cavity Theory
  • 33.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Spencer-Attix kavitetsteori2001Report (Other academic)
    Abstract [en]

    Spencer-Attix kavitetsteori behandlar energideponeringen i en Bragg-Gray kavitet (detektor) inuti ett medium bestrålat med fotoner och med elektronjämvikt i mediet på kavitetens plats. Med en Bragg-Gray kavitet menas en kavitet så liten att

    • energideponeringen i kaviteten från elektroner frigjorda av fotoner i kaviteten är försumbar jämfört med energideponeringen från elektroner frigjorda av fotoner i omgivande mediet och som passerar in kaviteten
    • kaviteten skall inte nämnvärt störa fluensen av elektronerna i mediet, dvs kaviteten antas i varje punkt genomkorsad av samma fluens av elektroner, som finns i mediet i frånvaro av kaviteten
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    Spencer-Attix kavitetsteori
  • 34.
    Alm Carlsson, Gudrun
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Carlsson, Carl A.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Statistisk precision vid radioaktivitetsmätning och Aktivitetsbestämning ur uppmätt räknehastighet1974Report (Other academic)
    Abstract [sv]

    Radioaktiva sönderfall sker slumpmässigt och det är omöjligt att i förväg veta exakt när en viss atom sönderfaller. Allt man kan säga är att under en halveringstid är sannolikheten 0.5 att en atom sönderfaller och 0.5 att den förblir i sitt ursprungliga radioaktiva tillstånd. Detta gäller en enstaka atom, är det ett stort antal atomer kan man förutsäga att hälften av dem kommer att sönderfalla inom en halveringstid.

    Antag att i ett experiment aktiviteten av ett prov bestäms under en minut. Räknaren anger 1000 cpm, counts per minute. Om man räknar en gång till kanske scalern anger 985 cpm, nästa gång 1023 cpm osv Skulle man utföra mätningen 1000 gånger skulle man få värdet 1000 12 - 13 gånger, 960 och faktiskt 1040 skulle man få 5-6 gångeroch 940 eller 1060 2 gånger. Detta beror inte på något experimentellt fel eller på någon speciell teknik som experimenttorn använder utan på de statistiska fluktuationerna. (Skulle man få värdet 1000 varje gång skall man kontrollera räknaren, någon kanske har ställt in pre-set counts 1000, dvs då är något fel).

    Vi skall i denna rapport se hur de statistiska fluktuationerna påverkar mätresultaten, hur osäkerheten presenteras och hur man gör en aktivitetsbestämning ur en uppmätt räknehastighet.

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    Statistisk precision vid radioaktivitetsmätning och Aktivitetsbestämning ur uppmätt räknehastighet
  • 35.
    Alm Carlsson, Gudrun
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Carlsson, Carl A.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Pettersson, Håkan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Riskuppskattningar och strålskydds-rekommendationer: Vår strålningsmiljö1991Report (Other academic)
    Abstract [sv]

    Människan har i alla tider varit utsatt för joniserande strålning. Kosmiskstrålning och naturligt radioaktiva nuklider i vår omgivning och i vår kropp ger ett årligtbidrag till den absorberade dosen i hela kroppen, som i genomsnitt för människorna påjorden uppgår till 1 mGy/år (1Gy = 1 J/kg). Det finns områden på jorden där stråldosenfrån naturlig strålning är 10-100 ggr större, jfr avsnittet "Vår strålningsmiljö".

    I slutet av 1800-talet upptäckte Röntgen röntgenstrålningen och Becquerel den naturligaradioaktiviteten. Människan fick därmed för första gången tillgång till starka källor avjoniserande strålning. Dessa togs snabbt i bruk framförallt inom medicinsk röntgendiagnostikoch radioterapi. Man gjorde snart bittra erfarenheter av den joniserandestrålningens skadliga biologiska verkningar efter höga stråldoser. Fram till år 1922 hadec:a 100 radiologer dött av strålskador. Man insåg att något måste göras för att förbättraläget för personalen och år 1928 bildades ICRP (International Commission on RadiationProtection). ICRP ger ut rekommendationer för strålskydd, som ligger till grund förnationella lagar och förordningar över hela världen.

    Den förhållandevis långa erfarenhet människan har av joniserande strålning och denlätthet med vilken även små stråldoser kan mätas har gett oss stränga normer vad gällerhanteringen av producerade strålkällor. Många har därför uppfattningen att joniserandestrålning är en exklusiv miljökomponent. Så är knappast fallet. Förutom att vi alltid varitnaturligt bestrålade finns det idag anledning att förmoda att den kemiska nedsmutsningenav miljön är ett långt allvarligare hot mot vårt välbefinnande än den nuvarandeanvändningen av producerade strålkällor. En rättvis bedömning av olika miljökomponenterkan endast göras den gång alla mäts med samma mått. Arbete med dennainriktning pågår med strålskydds-verksamheten som förebild.

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    Riskuppskattningar och strålskydds-rekommendationer : Vår strålningsmiljö
  • 36.
    Alm Carlsson, Gudrun
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Ekberg, Stefan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Helmrot, Ebba
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Lindström, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Matscheko, Georg
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Nilsson, Håkan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Sandborg, Michael
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Stenström, Mats
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Monte Carlo metoden: ett verktyg inom strålningsfysiken1995Report (Other academic)
    Abstract [sv]

    Detta kompendium är tänkt att användas som ett propedeutiskt kursmaterial för kursdeltagare i kursen "Monte Carlo simulering av foton- och elektrontransport vid diagnostiska och radioterapeutiska strålkvaliteter".

    Först följer en kort repetition av den grundläggande statistik som utnyt1jas i beräkningarna. Därefter följer en beskrivning av slumptal. det fundament som metoden bygger på. Vidare beskrivs val ur olika frekvensfunktioner. Valet kan även göras ur så kallade falska fördelningar för att reducera variansen i den skattade storheten. Metoderna belyses i ett avsnitt om problemlösningsmetodik. först i allmänna termer för att sen gå in på ett specifikt problem (Buffons nålproblem) där en analys och strukturering av problemet görs varefter flödesschema och kodning exemplifieras. Så följer två moment där en beskrivning görs av färderna av fotoner respektive elektroner genom materia. För elektronfärderna gör man en indelning i klass 1- och klass II-färder. Vad detta innebär och hur deltapartiklar tas om hand beskrivs i ett kapitel. Till sist kommer en kort introduktion till de tre laborationerna med laborationshandledningar. Speciell vikt har lagts vid att initiera laboranten att fundera på fysiken i de simulerade experimenten.

    Detta kompendium har tillkommit som examinationsarbete vid en kurs i "Monte Carlo simulering av foton- och elektrontransport vid diagnostiska och radioterapeutiska strålkvaliteter", med andra ord den kurs du själv nu ämnar studera. Författarna önskar dig lycka till med kursen och hoppas att du kommer att få glädje av den. Speciellt hoppas vi att denna skrift ska underlätta för dig att tillgodogöra dig informationen vid föreläsningarna och under laborationerna.

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    Monte Carlo metoden : ett verktyg inom strålningsfysiken
  • 37.
    Amendoeira, Isabel
    et al.
    Ctr Hosp Univ S Joao CHUSJ, Portugal; Ipatimup, Portugal.
    Arcidiacono, Paolo Giorgio
    IRCCS Osped San Raffaele Milano, Italy.
    Barizzi, Jessica
    Ist Cantonale Patol, Switzerland.
    Capitanio, Arrigo
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Clinical pathology.
    Cuatrecasas, Miriam
    Univ Barcelona, Spain.
    Matteo, Francesco Maria Di
    Fdn Policlin Univ Campus Biomed, Italy.
    Doglioni, Claudio
    Ist Sci San Raffaele, Italy.
    Fukushima, Noriyoshi
    Jichi Med Univ, Japan.
    Fulciniti, Franco
    Ist Cantonale Patol, Switzerland.
    Gines, Angels
    Hosp Clin Barcelona, Spain.
    Giovannini, Marc
    Paoli Calmettes Inst, France.
    Zaibo, Li
    Ohio State Univ, OH 43210 USA.
    Lopes, Joanne
    Ctr Hosp Univ S Joao CHUSJ, Portugal; Ipatimup, Portugal.
    Lujan, Giovanni
    Ohio State Univ, OH 43210 USA.
    Parisi, Alice
    Azienda Osped Univ Integrata Verona, Italy.
    Poizat, Flora
    Inst Paoli Calmettes, France.
    Bonetti, Luca Reggiani
    Univ Modena & Reggio Emilia, Italy.
    Stigliano, Serena
    Fdn Policlin Univ Campus Biomed, Italy.
    Taffon, Chiara
    Fdn Policlin Univ Campus Biomed, Italy.
    Verri, Martina
    Fdn Policlin Univ Campus Biomed, Italy.
    Crescenzi, Anna
    Fdn Policlin Univ Campus Biomed, Italy.
    New digital confocal laser microscopy may boost real-time evaluation of endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) from solid pancreatic lesions: Data from an international multicenter study2022In: EBioMedicine, E-ISSN 2352-3964, Vol. 86, article id 104377Article in journal (Refereed)
    Abstract [en]

    Background Pancreatic cancer is an aggressive malignancy and a leading cause of cancer death worldwide; its lethality is partly linked to the difficulty of early diagnosis. Modern devices for endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) were recently developed to improve targeting and sampling of small lesions, but innovative technologies for microscopic assessment are still lacking. Ex vivo fluorescence confocal laser microscopy (FCM) is a new digital tool for real-time microscopic assessment of fresh unfixed biological specimens, avoiding conventional histological slide preparation and potentially being highly appealing for EUS-FNB specimens. Methods This study evaluated the possible role of FCM for immediate evaluation of pancreatic specimens from EUS-FNB. It involved comparison of the interobserver agreement between the new method and standard histological analysis during international multicenter sharing of digital images. Digital images from 25 cases of EUS-FNB obtained with real-time FCM technology and 25 paired digital whole-slide images from permanent conventional paraffin sections were observed by 10 pathologists from different Institutions in Europe, Japan, and the United States, in a blinded manner. The study evaluated 500 observations regarding adequacy, morphological clues, diagnostic categories, and final diagnosis. Findings Statistical analysis showed substantial equivalence in the interobserver agreement among pathologists using the two techniques. There was also good inter-test agreement in determining sample adequacy and when assigning a diagnostic category. Among morphological features, nuclear enlargement was the most reproducible clue, with very good inter-test agreement. Interpretation Findings in this study are from international multicenter digital sharing and are published here for the first time. Considering the advantages of FCM digital diagnostics in terms of reduced time and unaltered sample maintenance, the ex vivo confocal laser microscopy may effectively improve traditional EUS-FNB diagnostics, with significant implications for planning modern diagnostic workflow for pancreatic tumors. Copyright (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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  • 38. Andersson, A
    et al.
    Carlsson, J
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Hansson, T
    Söderfeldt, B
    Comparison of sign language production and meaningless hand movements by fMRI1998Conference paper (Other academic)
  • 39.
    Andersson, Roland
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Department of Surgery, County Hospital Ryhov, Jönköping, Sweden.
    Triaging with Clinical Scoring Systems Can Reduce CT Use in Patients Suspected of Having Appendicitis2022In: Radiology, ISSN 0033-8419, E-ISSN 1527-1315, Vol. 302, no 3Article in journal (Refereed)
  • 40.
    Andersson, Thord
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Karlsson, Anette
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Smedby, Örjan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Consistent intensity inhomogeneity correction in water–fat MRI2015In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 42, no 2, p. 468-476Article in journal (Refereed)
    Abstract [en]

    PURPOSE:

    To quantitatively and qualitatively evaluate the water-signal performance of the consistent intensity inhomogeneity correction (CIIC) method to correct for intensity inhomogeneities METHODS: Water-fat volumes were acquired using 1.5 Tesla (T) and 3.0T symmetrically sampled 2-point Dixon three-dimensional MRI. Two datasets: (i) 10 muscle tissue regions of interest (ROIs) from 10 subjects acquired with both 1.5T and 3.0T whole-body MRI. (ii) Seven liver tissue ROIs from 36 patients imaged using 1.5T MRI at six time points after Gd-EOB-DTPA injection. The performance of CIIC was evaluated quantitatively by analyzing its impact on the dispersion and bias of the water image ROI intensities, and qualitatively using side-by-side image comparisons.

    RESULTS:

    CIIC significantly ( P1.5T≤2.3×10-4,P3.0T≤1.0×10-6) decreased the nonphysiological intensity variance while preserving the average intensity levels. The side-by-side comparisons showed improved intensity consistency ( Pint⁡≤10-6) while not introducing artifacts ( Part=0.024) nor changed appearances ( Papp≤10-6).

    CONCLUSION:

    CIIC improves the spatiotemporal intensity consistency in regions of a homogenous tissue type. J. Magn. Reson. Imaging 2014.

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  • 41.
    Andersson, Thord
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Romu, Thobias
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Forsgren, Mikael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Endocrinology.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Self-calibrated DCE MRI using Multi Scale Adaptive Normalized Averaging (MANA)2012In: Proceedings of the annual meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), 2012, 2012Conference paper (Other academic)
  • 42.
    Ardenfors, Oscar
    et al.
    Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Stockholm University.
    Josefsson, Dan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dasu, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Are IMRT treatments in the head and neck region increasing the risk of secondary cancers?2014In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 53, no 8, p. 1041-1047Article in journal (Refereed)
    Abstract [en]

    Background: Intensity modulated radiation therapy (IMRT) has been increasingly employed for treating head and neck (H&N) tumours due to its ability to produce isodoses suitable for the complex anatomy of the region. The aim of this study was to assess possible differences between IMRT and conformal radiation therapy (CRT) with regard to risk of radiation-induced secondary malignancies for H&N tumours.

    Material and Methods: IMRT and CRT plans were made for 10 H&N adult patients and the resulting treatment planning data were used to calculate the risk of radiation-induced malignancies in four different tissues. Three risk models with biologically relevant parameters were used for calculations. The influence of scatter radiation and repeated imaging sessions has also been investigated.

    Results: The results showed that the total lifetime risks of developing radiation-induced secondary malignancies from the two treatment techniques, CRT and IMRT, were comparable and in the interval 0.9-2.5%. The risk contributions from the primary beam and scatter radiation were comparable, whereas the contribution from repeated diagnostic imaging was considerably smaller.

    Conclusion: The results indicated that the redistribution of the dose characteristic to IMRT leads to a redistribution of the risks in individual tissues. However, the total levels of risk were similar between the two irradiation techniques considered.

  • 43.
    Arvidsson, Ida
    et al.
    Lund Univ, Sweden.
    Overgaard, Niels Christian
    Lund Univ, Sweden.
    Astrom, Kalle
    Lund Univ, Sweden.
    Heyden, Anders
    Lund Univ, Sweden.
    Figueroa, Miguel Ochoa
    Region Östergötland, Heart Center, Department of Clinical Physiology in Linköping. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Frias Rose, Miguel Jeronimo
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences.
    Davidsson, Anette
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart Center, Department of Clinical Physiology in Linköping.
    Prediction of Obstructive Coronary Artery Disease from Myocardial Perfusion Scintigraphy using Deep Neural Networks2021In: 2020 25TH INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION (ICPR), IEEE COMPUTER SOC , 2021, p. 4442-4449Conference paper (Refereed)
    Abstract [en]

    For diagnosis and risk assessment in patients with stable ischemic heart disease, myocardial perfusion scintigraphy is one of the most common cardiological examinations performed today. There are however many motivations for why an artificial intelligence algorithm would provide useful input to this task. For example to reduce the subjectiveness and save time for the nuclear medicine physicians working with this time consuming task. In this work we have developed a deep learning algorithm for multi-label classification based on a convolutional neural network to estimate the probability of obstructive coronary artery disease in the left anterior artery, left circumflex artery and right coronary artery. The prediction is based on data from myocardial perfusion scintigraphy studies conducted in a dedicated Cadmium-Zinc-Telluride cardio camera (D-SPECT Spectrum Dynamics). Data from 588 patients was available, with stress images in both upright and supine position, as well as a number of auxiliary parameters such as angina symptoms and age. The data was used to train and evaluate the algorithm using 5-fold cross-validation. We achieve state-of-the-art results for this task with an area under the receiver operating characteristics curve of 0.89 as average on per-vessel level and 0.95 on per-patient level.

  • 44.
    Arvidsson, Ida
    et al.
    Lund Univ, Sweden.
    Overgaard, Niels Christian
    Lund Univ, Sweden.
    Davidsson, Anette
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart Center, Department of Clinical Physiology in Linköping.
    Frias Rose, Miguel Jeronimo
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences.
    Astrom, Kalle
    Lund Univ, Sweden.
    Figueroa, Miguel Ochoa
    Region Östergötland, Heart Center, Department of Clinical Physiology in Linköping. Linköping University, Department of Health, Medicine and Caring Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Heyden, Anders
    Lund Univ, Sweden.
    Detection of left bundle branch block and obstructive coronary artery disease from myocardial perfusion scintigraphy using deep neural networks2021In: MEDICAL IMAGING 2021: COMPUTER-AIDED DIAGNOSIS, SPIE-INT SOC OPTICAL ENGINEERING , 2021, Vol. 11597, article id 115970NConference paper (Refereed)
    Abstract [en]

    Myocardial perfusion scintigraphy, which is a non-invasive imaging technique, is one of the most common cardiological examinations performed today, and is used for diagnosis of coronary artery disease. Currently the analysis is performed visually by physicians, but this is both a very time consuming and a subjective approach. These are two of the motivations for why an automatic tool to support the decisions would be useful. We have developed a deep neural network which predicts the occurrence of obstructive coronary artery disease in each of the three major arteries as well as left bundle branch block. Since multiple, or none, of these could have a defect, this is treated as a multi-label classification problem. Due to the highly imbalanced labels, the training loss is weighted accordingly. The prediction is based on two polar maps, captured during stress in upright and supine position, together with additional information such as BMI and angina symptoms. The polar maps are constructed from myocardial perfusion scintigraphy examinations conducted in a dedicated Cadmium-Zinc-Telluride cardio camera (D-SPECT Spectrum Dynamics). The study includes data from 759 patients. Using 5-fold cross-validation we achieve an area under the receiver operating characteristics curve of 0.89 as average on per-vessel level for the three major arteries, 0.94 on per-patient level and 0.82 for left bundle branch block.

  • 45.
    Asa, Sylvia
    et al.
    Department of Pathology, University Health Network, Toronto, Ontario, Canada.
    Bodén, Anna
    Linköping University, Department of Clinical and Experimental Medicine, Divison of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Clinical pathology.
    Treanor, Darren
    University of Leeds, and Leeds Teaching Hospitals NHS Trust Leeds, UK.
    Jarkman, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Divison of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Clinical pathology.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Pantatnowitz, Liron
    Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, USA.
    2020 vision of digital pathology in action2019In: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 10, no 27Article in journal (Other academic)
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  • 46. Bagh, K
    et al.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Characterization of the cell-wall associated acid phosphatases of catharanthus roseus1990Conference paper (Other academic)
  • 47.
    Bakken, Ingvild M.
    et al.
    Sorlandet Hosp Arendal, Norway.
    Jackson, Catherine J.
    Ifocus Eye Clin, Norway; Univ Oslo, Norway.
    Utheim, Tor P.
    Sorlandet Hosp Arendal, Norway; Oslo Univ Hosp, Norway; Univ Agder, Norway.
    Villani, Edoardo
    Univ Milan, Italy; San Giuseppe Hosp, Italy.
    Hamrah, Pedram
    Tufts Univ, MA 02111 USA.
    Kheirkhah, Ahmad
    UT Hlth San Antonio, TX USA.
    Nielsen, Esben
    Aarhus Univ Hosp, Denmark.
    Hau, Scott
    Moorfields Eye Hosp NHS Fdn Trust, England; UCL Inst Ophthalmol, England.
    Lagali, Neil
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Sensory Organs and Communication. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping. Sorlandet Hosp Arendal, Norway.
    The use of in vivo confocal microscopy in fungal keratitis - Progress and challenges2022In: Ocular Surface, ISSN 1542-0124, Vol. 24, p. 103-118Article in journal (Refereed)
    Abstract [en]

    Fungal keratitis (FK) is a serious and sight-threatening corneal infection with global reach. The need for prompt diagnosis is paramount, as a delay in initiation of treatment could lead to irreversible vision loss. Current "gold standard" diagnostic methods, namely corneal smear and culture, have limitations due to diagnostic insensitivity and their time-consuming nature. PCR is a newer, complementary method used in the diagnosis of fungal keratitis, whose results are also sample-dependent. In vivo confocal microscopy (IVCM) is a promising complementary diagnostic method of increasing importance as it allows non-invasive real-time direct visualization of potential fungal pathogens and manifesting infection directly in the patients cornea. In numerous articles and case reports, FK diagnosis by IVCM has been evaluated, and different features, approaches, sensitivity/specificity, and limitations have been noted. Here, we provide an up-to-date, comprehensive review of the current literature and present the authors combined recommendations for fungal identification in IVCM images, while also looking to the future of FK assessment by IVCM using artificial intelligence methods.

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  • 48.
    Barazanji, Nawroz
    et al.
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Mag- tarmmedicinska kliniken.
    Hamilton, Paul J.
    Linköping University, Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Icenhour, Adriane
    Ruhr University Bochum, Bochum, Germany.
    Simon, Rozalyn
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bednarska, Olga
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Mag- tarmmedicinska kliniken.
    Tapper, Sofie
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Tisell, Anders
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Medical radiation physics. Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine.
    Lundberg, Peter
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Engström, Maria
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Walter, Susanna
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Mag- tarmmedicinska kliniken.
    Irritable bowel syndrome in women: Association between decreased insular subregion volumes and gastrointestinal symptoms2022In: NeuroImage: Clinical, E-ISSN 2213-1582, Vol. 35, article id 103128Article in journal (Refereed)
    Abstract [en]

    Irritable bowel syndrome (IBS) is a chronic pain disorder characterized by disturbed interactions between the gut and the brain with depression as a common comorbidity. In both IBS and depression, structural brain alterations of the insular cortices, key structures for pain processing and interoception, have been demonstrated but the specificity of these findings remains unclear. We compared the gray matter volume (GMV) of insular cortex (IC) subregions in IBS women and healthy controls (HC) and examined relations to gastrointestinal (GI) symptoms and glutamate + glutamine (Glx) concentrations. We further analyzed GMV of IC subregions in women with major depression (MDD) compared to HC and addressed possible differences between depression, IBS, IBS with depression and HC.

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  • 49.
    Barranco, Isabel
    et al.
    Univ Bologna, Italy.
    Rubio, Camila P.
    Univ Autonoma Barcelona, Spain; Univ Murcia, Spain.
    Tvarijonaviciute, Asta
    Univ Murcia, Spain; Univ Murcia, Spain.
    Rodriguez-Martinez, Heriberto
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Children's and Women's Health. Linköping University, Faculty of Medicine and Health Sciences.
    Roca, Jordi
    Univ Murcia, Spain.
    Measurement of Oxidative Stress Index in Seminal Plasma Can Predict In Vivo Fertility of Liquid-Stored Porcine Artificial Insemination Semen Doses2021In: Antioxidants, ISSN 2076-3921, Vol. 10, no 8, article id 1203Article in journal (Refereed)
    Abstract [en]

    The study evaluated the relation between the oxidative stress index (OSI) in porcine seminal plasma (n = 76) with sperm resilience and in vivo fertility (farrowing rate and litter size of 3137 inseminated sows) of liquid-stored artificial insemination (AI) semen doses. The OSI was assessed as the ratio of advanced oxidation protein products to Trolox-equivalent antioxidant capacity, both measured using an automated analyzer. Sperm motility (computer-assisted sperm analyzer) and viability (flow cytometry) were evaluated in semen AI-doses at 0 and 72 h of storage at 17 degrees C. Sperm resilience was defined as the difference between storage intervals. Semen AI-doses were hierarchically clustered as having high, medium and low seminal OSI (p &lt; 0.001) with those of low displaying higher resilience (p &lt; 0.01). Boars were hierarchically clustered into two groups (p &lt; 0.001) as having either positive or negative farrowing rate and litter size deviation; the negative one showing higher seminal OSI (p &lt; 0.05). In sum, seminal OSI was negatively related to sperm motility and the in vivo fertility of liquid-stored boar semen AI-doses, with the receiver operating characteristic curve presenting seminal OSI as a good predictive biomarker of in vivo fertility of AI-boars (area under the curve: 0.815, p &lt; 0.05).

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  • 50.
    Bar-Sever, Zvi
    et al.
    Tel Aviv Univ, Israel.
    Biassoni, Lorenzo
    Great Ormond St Hosp Children NHS Fdn Trust, England.
    Shulkin, Barry
    St Jude Childrens Res Hosp, TN 38105 USA.
    Kong, Grace
    Peter MacCallum Canc Ctr, Australia.
    Hofman, Michael S.
    Peter MacCallum Canc Ctr, Australia.
    Lopci, Egesta
    Humanitas Clin and Res Hosp, Italy.
    Manea, Irina
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Koziorowski, Jacek
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Castellani, Rita
    Ist Nazl Tumori, Italy.
    Boubaker, Ariane
    Clin Source, Switzerland.
    Lambert, Bieke
    Univ Ghent, Belgium.
    Pfluger, Thomas
    Ludwig Maximilian Univ Hosp, Germany.
    Nadel, Helen
    British Columbia Childrens Hosp, Canada.
    Sharp, Susan
    Cincinnati Childrens Hosp Med Ctr, OH 45229 USA.
    Giammarile, Francesco
    IAEA, Austria.
    Guidelines on nuclear medicine imaging in neuroblastoma2018In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 45, no 11, p. 2009-2024Article in journal (Refereed)
    Abstract [en]

    Nuclear medicine has a central role in the diagnosis, staging, response assessment and long-term follow-up of neuroblastoma, the most common solid extracranial tumour in children. These EANM guidelines include updated information on I-123-mIBG, the most common study in nuclear medicine for the evaluation of neuroblastoma, and on PET/CT imaging with F-18-FDG, F-18-DOPA and Ga-68-DOTA peptides. These PET/CT studies are increasingly employed in clinical practice. Indications, advantages and limitations are presented along with recommendations on study protocols, interpretation of findings and reporting results.

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