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Personal exposure to static and time-varying magnetic fields during MRI system test procedures

✍ Scribed by Frank de Vocht; Floris Muller; Hans Engels; Hans Kromhout

Publisher
John Wiley and Sons
Year
2009
Tongue
English
Weight
238 KB
Volume
30
Category
Article
ISSN
1053-1807

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Purpose:

To assess personal time‐weighted average (TWA) static magnetic field and time‐varying magnetic field exposure for several system testing tasks routinely conducted by engineers at an MRI manufacturing plant.

Materials and Methods:

Personal exposure was measured using a personal dosimeter that measured B and dB/dt in all three orthogonal directions with a 1 Hz frequency. TWA exposure was calculated and random effects and linear mixed effects models were used to assess exposure levels and variability.

Results:

Whereas full‐body peak (2T) and TWA (200 mT/8 h) exposure limits for the static magnetic field originally proposed by ICNIRP were not exceeded, time‐varying magnetic field peaks (dB/dt) did exceed the proposed threshold value (767.9 mT/s) suggested by IEEE on several occasions at the 3.0 Tesla (T) whole‐body cylindrical system.

Conclusion:

TWA exposure levels are well below the proposed limit values, but peak exposure limits are exceeded during certain procedures performed on 1.0T to 3.0T systems. J. Magn. Reson. Imaging 2009;30:1223–1228. © 2009 Wiley‐Liss, Inc.

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