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Occupational exposure in MR facilities due to movements in the static magnetic field
Author(s) -
Andreuccetti Daniele,
Biagi Laura,
Burriesci Giancarlo,
Cannatà Vittorio,
Contessa Gian Marco,
Falsaperla Rosaria,
Genovese Elisabetta,
Lodato Rossella,
Lopresto Vanni,
Merla Caterina,
Napolitano Antonio,
Pinto Rosanna,
Tiberi Gianluigi,
Tosetti Michela,
Zoppetti Nicola
Publication year - 2017
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.12537
Subject(s) - magnetostatics , limit (mathematics) , magnetic field , limits of agreement , directive , magnetic resonance imaging , flux (metallurgy) , compliance (psychology) , physics , statistics , nuclear medicine , medicine , mathematics , computer science , materials science , psychology , radiology , mathematical analysis , quantum mechanics , metallurgy , programming language , social psychology
Purpose The exposure of operators moving in the static field of magnetic resonance ( MR ) facilities was assessed through measurements of the magnetic flux density, which is experienced as variable in time because of the movement. Collected data were processed to allow the comparison with most recent and authoritative safety standards. Methods Measurements of the experienced magnetic flux density B were performed using a probe worn by volunteers moving in MR environments. A total of 55 datasets were acquired nearby a 1.5 T, 3 T, and 7 T whole body scanners. Three different metrics were applied: the maximum intensity of B, to be compared with 2013/35/ EU Directive exposure limit values for static fields; the maximum variation of the vector B on every 3s‐interval, for comparison with the ICNIRP ‐2014 basic restriction aimed at preventing vertigo effects; two weighted‐peak indices (for “sensory” and “health” effects: SENS ‐ WP , HLTH ‐ WP ), assessing compliance with ICNIRP ‐2014 and EU Directive recommendations intended to prevent stimulation effects. Results Peak values of | B | were greater than 2 T in nine of the 55 datasets. All the datasets at 1.5 T and 3 T were compliant with the limit for vertigo effects, whereas six datasets at 7 T turned out to be noncompliant. At 7 T, all 36 datasets were noncompliant for the SENS ‐ WP index and 26 datasets even for the HLTH ‐ WP one. Conclusions Results demonstrate that compliance with EU Directive limits for static fields does not guarantee compliance with ICNIRP ‐2014 reference levels and clearly show that movements in the static field could be the key component of the occupational exposure to EMF in MR facilities.