Monitoring the head exposure of MRI workers around 3 T, 7 T, and 11.7 T scanners using smart goggles equipped with a network of magnetometers.

Abstract

Purpose: The aim of this paper is to introduce a new magnetic field exposimeter device that consists of goggles equipped with magnetic sensors for the assessment of the field exposure of MRI workers' heads. This is not possible with conventional pocket exposimeters. Hence, this device allows head-level field exposure to be measured, which can induce physiological effects on MRI workers, and which are required to be covered by managing the laboratory-related safety hazards directive 2013/35/EU.

Methods: Using on-chip monolithic three-axis Hall effect magnetometers, recently introduced on the market, we developed an exposimeter with unprecedented accuracy, which allows the measurement of the magnetic field closed to the organs which are the most impacted by strong magnetic fields: the brain, the eyes, and the tongue.

Results: The exposimeter prototypes were successfully tested around 3 T, 7 T, and 11.7 T MRI scanners on different workers and volunteers in real conditions. Comparisons with chest-level measurements lead typically to lower values than exposure recorded at the head-level, confirming the need for such head-level assessments. Exposure of the head above the limits established by the directive was also recorded (>2 T or >2.7 T/s).

Conclusion: This new exposimeter allows for a more accurate assessment of field exposure of MRI workers. Further improvements in the miniaturization and the usability of the exposimeter will allow us to disseminate the device and open the way to a larger-scale study.