| Analysis and measurements of magnetic field exposures for healthcare workers in selected MR environments. | |
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MedLine Citation:
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PMID: 18390326 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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There are concerns about workers repeatedly exposed to magnetic fields exceeding regulatory limits with respect to modern magnetic resonance imaging (MRI). As a result, there is need for an ambulatory magnetic field dosimeter capable of measuring these fields in and around an MRI scanner in order to evaluate the regulatory guidelines and determine any underlying exposure risks. This study presents results of tri-axial measurements using an ambulatory magnetic field dosimeter worn by workers during normal working shifts. We recorded and analyzed magnetic field exposures in and around 1.5 T, 2 T, and 4 T magnets during routine patient procedures. The data was integrated and averaged over time and evaluated against the latest exposure standards. Time-varying magnetic fields occur when individuals move through spatially non-uniform static magnetic fields or during gradient-pulsed magnetic fields or a combination of both. Our previous numerical analysis shows that at certain positions surrounding the MRI scanner ends, such fields may induce current densities and electric fields that may exceed the relevant EU, ICNIRP, and IEEE standards. A high-speed acquisition version of the dosimeter measured gradient- pulsed fields at positions accessible by MRI workers near the scanner ends, and the results were evaluated and compared against the numerical simulations and the standards. Our measurements confirm that workers can be exposed to magnetic fields exceeding the guidelines at positions near the gradient coil ends during clinical imaging and a high degree of correlation exists with the numerical results. While the time-weighted average magnetic field exposures in 1.5 T, 2 T, and 4 T were all within the regulatory limits during static magnetic field measurements, the peak limits for the head can be exceeded in some circumstances. This study presents a small number of routine shifts of data that provide indicative results of magnetic field exposure in real situations. |
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Authors:
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Miguel A Fuentes; Adnan Trakic; Stephan J Wilson; Stuart Crozier |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: IEEE transactions on bio-medical engineering Volume: 55 ISSN: 0018-9294 ISO Abbreviation: IEEE Trans Biomed Eng Publication Date: 2008 Apr |
Date Detail:
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Created Date: 2008-04-08 Completed Date: 2008-05-14 Revised Date: 2009-11-11 |
Medline Journal Info:
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Nlm Unique ID: 0012737 Medline TA: IEEE Trans Biomed Eng Country: United States |
Other Details:
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Languages: eng Pagination: 1355-64 Citation Subset: IM |
Affiliation:
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School of Information Technology, University of Queensland, St. Lucia, Australia. stuart@itee.uq.edu.au |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Australia Body Burden* Electromagnetic Fields* Humans Magnetic Resonance Imaging* Maximum Allowable Concentration Medical Staff* Occupational Exposure / analysis* Radiation Dosage Radiation Monitoring / methods* Radiation Protection / methods* Relative Biological Effectiveness Reproducibility of Results Sensitivity and Specificity |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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