A novel tool for estimation of magnetic resonance occupational exposure to spatially varying magnetic fields.

ABSTRACT

OBJECT Staff operating in the environment of magnetic resonance imaging (MRI) scanners are exposed daily to static magnetic fields (MFs). To protect workers several guidelines are present in literature reporting exposure limits values expressed in terms of magnetic flux density or induced current density. We present here a novel tool for estimating the induced current density due to worker movement in the MR environment. MATERIALS AND METHODS: A Matlab script was created to estimate the induced current density J due to operator movements along a chosen walking path. RESULTS: The induced current density associated with any worker's movements during MR procedures is dependent on the walking speed and on the spatial gradient fields associated with a specific path. Some examples of possible worker paths were considered here for a 3 T MR scanner and a maximum value of 160 cm/s walking speed. CONCLUSION: This tool permits one to find exposure level for specific worker walking path and speed; it can be used as assessment tool in any MRI centre and for workers safety education. It is valid for any kind of commercial scanner because it requires only the knowledge of the MR scanner room map with isogauss lines.