The electromagnetic environment of Magnetic Resonance Imaging systems. Occupational exposure assessment reveals RF harmonics

[摘要] Magnetic Resonance Imaging (MRI) systems played a crucial role in the postponement of the former occupational electromagnetic fields (EMF) European Directive (2004/40/EC) and in the formation of the latest exposure limits adopted in the new one (2013/35/EU). Moreover, the complex MRI environment will be finally excluded from the implementation of the new occupational limits, leading to an increased demand for Occupational Health and Safety (OHS) surveillance. The gradient function of MRI systems and the application of the RF excitation frequency result in low and high frequency exposures, respectively. This electromagnetic field exposure, in combination with the increased static magnetic field exposure, makes the MRI environment a unique case of combined EMF exposure. The electromagnetic field levels in close proximity of different MRI systems have been assessed at various frequencies. Quality Assurance (QA) & safety issues were also faced. Preliminary results show initial compliance with the forthcoming limits in each different frequency band, but also revealed peculiar RF harmonic components, of no safety concern, to the whole range detected (20-1000MHz). Further work is needed in order to clarify their origin and characteristics.

[发布机构] Hazardous Agents Dep., Hellenic Ministry of Labor, 29 Stadiou str., GR10110, Greece^1;Greek Atomic Energy Commission, Non-Ionizing Rad. Off., POBox60092, GR15310, Greece^2;Department of Medical Physics, University of Thessaly, Larissa; GR41500, Greece^3;Department of Medical Physics, University of Crete, POBox1352, GR71201, Greece^4

[效力级别] 医药卫生 [学科分类] 卫生学

[关键词] Electromagnetic environments;Electromagnetic field (EMF);Electromagnetic field exposure;Low and high frequencies;Magnetic Resonance Imaging (MRI);Occupational exposure assessments;Occupational health and safety;Static magnetic fields