Electromagnetic Dosimetry
Electromagnetic Dosimetry
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Summary
This group supports the agency’s regulatory research roles by advancing our knowledge on the complex interactions between electromagnetic (EM) fields and the human body or other objects such as models of cardiac pacemakers implanted in the body. We coordinate research closely with the EM modeling program. The research combines computational models and experimental techniques applied to several areas of clinical significance, including the: 1) analysis of radiofrequency (RF)-induced heating in patients with implanted medical devices undergoing Magnetic Resonance Imaging (MRI); and 2) assessment of electromagnetic energy deposition by diathermy and airport millimeter wave sources such as cellular phones and radio and television broadcast towers.
This program has a direct impact on the regulatory mission of the agency, as the tools developed by our research are used by industry in pre-market evaluation of safety and effectiveness of their medical devices. The research is funded by external support from the transportation security administration (TSA).
AIT scanner and a PMED being placed in it for testing.
Electric field plots in an MRI coil comparing measured with computed results.
Computed electric field plots in a human tissue model showing penetration depth.
The electromagnetic compatibility (EMC) and wireless lab has a long history of working with other federal agencies on issues involving medical device EMC. Presently, the EMC-wireless lab is engaged in an agreement with the Transportation Security Administration (TSA) to evaluate potential safety issues for the passengers screened and security personnel with the next generation of advanced imaging technology (AIT) millimeter waves (mmW) whole body security scanner systems. These AIT systems use small levels of radio waves in the mmW spectrum to help create the security screening image. TSA and FDA share common interest in assessing the potential risks for passengers with Personal Medical Electronic Devices (PMEDs) such as implanted cardiac pacemakers and cardioverter-defibrillators, implanted and body worn neurostimulators, and body worn insulin pumps. Measurements and analysis by the EMC-wireless lab researchers assessed the human exposure risks of passengers passing through an AIT and nearby security personnel finding these exposure levels to be many thousand times below the limits set by International radiation safety standards organizations. The research also included tests of several sample PMEDs for exposure to the AIT system as well as a novel system developed in the lab that simulates the AIT exposure in ways that can be more controlled. None of the PMEDs showed signs of effects during or after the AIT exposures
Current external funding sources
Transportation Security Administration (TSA)
Personnel
FDA Staff:
Howard Bassen, MSc
Leonardo Angelone, Ph.D.
Maria Iacono, Ph.D.
Wolfgang Kainz, Ph.D.
Sunder Rajan, Ph.D.
Research Fellows:
Elena Lucano
Gonzalo Mendoza
Amir Razjouyan
Peter Serano
Resource facilities
Hardware
- Magnetic resonance imaging (MRI) Gradient coil simulator with amplifiers (MRCOMP, Germany)
- Magnetic resonance imaging (MRI) coils (64MHz and 128MHz) (MITS, Zurich, Switzerland)
- DASY5 Robotic Electric and magnetic field measurements system (Zurich, Switzerland)
- 10 meter fully anechoic chamber
- Tissue implantable electric and magnetic field probes.
Software
- Sim4Life Electromagnetic and thermal solvers (SPEAG)
- SemcadX Electromagnetic and thermal solvers
- XFDTD (Remcom)
Relevant standards
IEEE Std C95.3.1™-2010, IEEE Recommended Practice for Measurements and Computations of Electric, Magnetic, and Electromagnetic Fields with Respect to Human Exposure to Such Fields, 0 Hz to 100 kHz
Sponsor IEEE International Committee on Electromagnetic Safety
IEEE Std 1528™-2003, IEEE Recommended Practice for Determining the Peak Spatial-Average Specific Absorption Rate (SAR) in the Human Head from Wireless Communications Devices: Measurement Techniques Sponsor Standards Coordinating Committee 34 (Product Performance Standards Relative to the Safe Use of Electromagnetic Energy)
Selected peer-review publications
- Bassen and Angelone, Evaluation of Unintended Electrical Stimulation from MR Gradient Fields. Frontiers in Bioscience 2012.
- Bassen and Mendoza, In-vitro mapping of E fields induced near pacemaker leads by simulated MR gradient fields, BioMedical Engineering OnLine 2009.
- Mattei et al. Complexity of MRI induced heating on metallic leads: experimental measurements of 374 configurations, BioMedical Engineering OnLine 2008.
- Park et al., A novel method to decrease electric field and SAR using an external high dielectric sleeve at 3 T head MRI: numerical and experimental results, IEEE Trans Biomed Eng. 2015.
- Liu et al., Numerical investigations of MRI RF field induced heating for external fixation devices, Biomedical Engineering Online 2013.
- Liu et al. Computational and experimental studies of an orthopedic implant: MRI-related heating at 1.5-T/64-MHz and 3-T/128-MHz. Journal of Magnetic Resonance Imaging, 2013.
- Cabot et al., Evaluation of the RF heating of a generic deep brain stimulator exposed in 1.5 T Magnetic resonance scanners, Bioelectromagnetics 2013.
- Bassen and Babij. Instrumentation and Experimental Measurements. Chapter 7, Biological Effects and Medical Application of Electromagnetic Energy, 1990.
- Bassen and Smith, The Electric Field Probe - A Review. IEEE Transactions on Antennas and Propagation, 1983.