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The influence of 1.5 and 3 T magnetic resonance unit magnetic fields on the movement of steel-jacketed projectiles in ordnance gelatin

Eggert, Sebastian ; Kubik-Huch, Rahel ; Lory, Martin ; Froehlich, John ; Gascho, Dominic ; Thali, Michael ; Bolliger, Stephan

In: Forensic Science, Medicine, and Pathology, 2015, vol. 11, no. 4, p. 544-551

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    Titre
    • The influence of 1.5 and 3 T magnetic resonance unit magnetic fields on the movement of steel-jacketed projectiles in ordnance gelatin
    Auteur
    • Eggert, Sebastian. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland
    • Kubik-Huch, Rahel. Department of Radiology, Kantonsspital Baden AG, Baden, Switzerland
    • Lory, Martin. Forensic Institute Zurich, Zurich, Switzerland
    • Froehlich, John. Federal Institute of Technology, Pharmaceutical Sciences, Zurich, Switzerland
    • Gascho, Dominic. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland
    • Thali, Michael. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland
    • Bolliger, Stephan. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Forensic Science, Medicine, and Pathology, 2015, vol. 11, no. 4, p. 544-551. Springer US; http://www.springer-ny.com
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:331030
    Summary
    Purpose: Ferromagnetic bullets can move in air or gelatin in magnetic resonance (MR) units. According to our experience, ferromagnetic bullets do not always present consistent movement. We examined factors affecting ferromagnetic projectile movement in a 1.5T and a 3T MR unit, focusing in this study on the steel-jacketed Swiss ordnance ammunition 7.5mm GP11 Suisse. Methods: Five 7.5mm GP11 Suisse bullets were embedded horizontally and vertically in 10% ordnance gelatin phantoms. Before and after exposing the bullets to 1.5T (Siemens) and 3T (Philips) MR units each bullet's position was documented by a CT scan. In a second phase, the magnetic polarization of the bullets in relation to the MR units was measured by a dry magnetic portable compass (Suunto). Results: Our results showed that the displacement of the bullets increased when subjected to a stronger magnetic field (max. Movement 1.5T: 24.4mm vs. 3T: 101.5mm) and that the position, i.e. orientation of the bullet toward the gantry, strongly influenced its mobility (horizontally embedded projectiles showed poor movement, vertically placed ones strong movement). One of the bullets presented a 180° rotation in the 3T MR unit. Magnetization and changing of the polarization of these ferromagnetic bullets is possible when subjected to MR units. Conclusion: In conclusion, the location of a bullet, and its orientation toward the gantry must be taken into account when assessing the risk of performing an MR examination on a gunshot victim in clinical and in forensic cases.