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Original article
Personal exposure to static and time-varying magnetic fields during MRI procedures in clinical practice in the UK
  1. Evridiki Batistatou1,
  2. Anna Mölter2,
  3. Hans Kromhout3,
  4. Martie van Tongeren4,
  5. Stuart Crozier5,
  6. Kristel Schaap3,
  7. Penny Gowland6,
  8. Stephen F Keevil7,8,
  9. Frank de Vocht9
  1. 1Centre for Occupational and Environmental Health, University of Manchester, Manchester, UK
  2. 2Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
  3. 3Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands
  4. 4Centre for Human Exposure Science, Institute of Occupational Medicine, Edinburgh, UK
  5. 5School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland, Australia
  6. 6School of Physics and Astronomy, The University of Nottingham, Nottingham, UK
  7. 7Department of Medical Physics, Guy's and St Thomas’ NHS Foundation Trust, London, UK
  8. 8Department of Biomedical Engineering, King's College London, London, UK
  9. 9School of Social and Community Medicine, University of Bristol, Bristol, UK
  1. Correspondence to Dr Frank de Vocht, School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol BS8 2PS, UK; frank.devocht{at}bristol.ac.uk

Abstract

Background MRI has developed into one of the most important medical diagnostic imaging modalities, but it exposes staff to static magnetic fields (SMF) when present in the vicinity of the MR system, and to radiofrequency and switched gradient electromagnetic fields if they are present during image acquisition. We measured exposure to SMF and motion-induced time-varying magnetic fields (TVMF) in MRI staff in clinical practice in the UK to enable extensive assessment of personal exposure levels and variability, which enables comparison to other countries.

Methods 8 MRI facilities across National Health Service sites in England, Wales and Scotland were included, and staff randomly selected during the days when measurements were performed were invited to wear a personal MRI-compatible dosimeter and keep a diary to record all procedures and tasks performed during the measured shift.

Results 98 participants, primarily radiographers (71%) but also other healthcare staff, anaesthetists and other medical staff were included, resulting in 149 measurements. Average geometric mean peak SMF and TVMF exposures were 448 mT (range 20–2891) and 1083 mT/s (9–12 355 mT/s), and were highest for radiographers (GM=559 mT and GM=734 mT/s). Time-weighted exposures to SMF and TVMF (GM=16 mT (range 5–64) and GM=14 mT/s (range 9–105)) and exposed-time-weighted exposures to SMF and TVMF (GM=27 mT (range 11–89) and GM=17 mT/s (range 9–124)) were overall relative low—primarily because staff were not in the MRI suite for most of their shifts—and did not differ significantly between occupations.

Conclusions These results are comparable to the few data available from the UK but they differ from recent data collected in the Netherlands, indicating that UK staff are exposed for shorter periods but to higher levels. These data indicate that exposure to SMF and TVMF from MRI scanners cannot be extrapolated across countries.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Footnotes

  • Twitter Follow Frank de Vocht at @frankdevocht

  • Contributors AM and FdV collected the data. EB conducted the statistical analyses and drafted the manuscript. All authors were involved in the planning of the study. All authors were involved in interpretation of the data and provided input in the consecutive iterations of the manuscript. All authors read and approved of the final version of the manuscript. FdV is the guarantor for this work.

  • Funding The study was funded by a research grant from The COLT Foundation (grant number CF/01/11).

  • Competing interests SC developed, produces and licenses the dosimeters used in this study through a University of Queensland company.

  • Ethics approval University of Manchester's Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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