Retrospective Assessment of Exposure to Static Magnetic Fields During Production and Development of Magnetic Resonance Imaging Systems

Abstract

At present, the relationship between chronic exposure to static magnetic fields (SMF) and health effects is unclear. We developed a task-based deterministic model for estimating historical electromagnetic field exposure from the static B-field (B0) of magnetic resonance imaging (MRI) systems, for a cohort of employees working at an MRI systems development and production facility. Technical maps describing the spatial distribution of fringe fields of B0 surrounding different types of MRI systems of various core strengths were exploited to derive estimates of static B0 exposure as a function of distance from the bore of the MRI system. Detailed information on tasks performed per exposed job and other model determinants were acquired through face-to-face interviews and used to derive base estimates of most recent exposure (2009) for each job title. The model was partially validated with actual exposure measurements. The exposure estimates from the deterministic model were used to construct a job-exposure matrix that will enable estimation of cumulative exposures for each cohort member. The generic approach described for estimating chronic MRI-related SMF exposure makes it universally applicable in other studies investigating health effects of MRI-related SMF exposure.

Searching for the Perfect Wave: The Effect of Radiofrequency Electromagnetic Fields on Cells

“…[110], a thorough investigation identified the structure and the professional categories most likely to be involved in the use of MRI that include people using MRI for clinical diagnostics, MR-guided medical interventions on patients. Bongers et al [111] carried out a study by interviewing and evaluating self-assessing workers employed in production and development of MRI systems. To evaluate the level of RF exposure and generate a predictive algorithm universally applicable to model and predict the level of exposure and the effect people working with and around MRI systems might experience.…”

Occupational exposure to electromagnetic fields in magnetic resonance environment: an update on regulation, exposure assessment techniques, health risk evaluation, and surveillance

“…For this reason, one of the first suggestions regards an exposure categorization for the different professions working with MRI equipment, that could be based, for example, on the nature of the fields they are exposed to, the time that they are exposed, and the procedures that they perform. Some tools generally used to assess exposure to potential health hazards in occupational epidemiological studies, such as the job-exposure matrix, could aid [9,168,169].…”

Development of hypertension after long-term exposure to static magnetic fields among workers from a magnetic resonance imaging device manufacturing facility

“…Occupational SMF exposure was estimated for MR workers using a facility specific historical SMF job exposure matrix (SMF-JEM) developed for this purpose (Bongers et al, 2013), because of paucity of (historical) personal exposure measurements. Historical company records from the salary administration documented employment and job mobility of workers between 1954 and 2010 within the manufacturing facility.…”

“…EMF exposure from a scan procedure as an MR-volunteer was regarded as a different type of EMF exposure than occupational exposure to SMF (the latter is assumed to also serve as a proxy for exposure to low-frequency TvMF from movement through the static magnetic stray field around a scanner (Bongers et al, 2013)). An MR-volunteer will move through the SMF during positioning in and upon leaving the bore, but will remain stationary for the duration of the scan procedure.…”

“…The largest groups of SMF-exposed workers (in the Netherlands) are found in clinical and research settings where MRI techniques are being applied (Schaap et al, 2013). Technicians/engineers developing and producing MRI systems, on the other hand, are presumed to have been longer, more frequently and higher exposed (Gowland, 2005), since they generally spend more time near and inside MRI scanners (of various stages of production), which are factors considered to be major determinants of exposure to SMF (Bongers et al, 2013;Fuentes et al, 2008;de Vocht et al, 2009). As part of their work, some of them will probably also have volunteered for image acquisition during the development and manufacturing of MRI scanners.…”