EU Directive 2004/40/EC Electromagnetic Fields The

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EU Directive 2004/40/EC Electromagnetic
Fields

• The Negative Impact on
• MRI Clinical Applications
• COCIR EMF TASK FORCE

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History, Status and Context
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EC Directive history and status

• In 1989, the European Commission was mandated to
  develop Directives protecting workers from
  potential hazards caused by physical agents
• 4 Directives have been developed
• vibration (2002/44/EC)
• acoustic noise (2003/10/EC)
• electromagnetic field (EMF) (2004/40/EC)
• optical radiation (2006/25/EC)
• EMF Directive published in April 2004
• Transposition into national law within 4 years,
  i.e. by 2008

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General COCIR statements

• Facts
• Directive 2004/40/EC covers minimum health and
  safety requirements regarding the exposure of
  workers arising from electromagnetic fields. The
  directive defines exposure limits up to 300 GHz
• The directive stipulates in any event, workers
  shall not be exposed above the exposure limit
  values
• Area of concern for COCIR
• The application of electromagnetic fields in
  Magnetic Resonance Imaging (MRI)
• COCIR issues
• Currently, these exposure limits are regularly
  exceeded with NO REPORTED NEGATIVE EFFECTS on
  either workers or gt500,000 patients worldwide.
• The EC directive will hamper use of MRI and
  prohibit future medical applications of MR.

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The Aims and Scope of the EMF Directive
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The EMF Directive

• Aims to protect workers from acute exposure to
  electromagnetic fields (EMF)
• Defines exposure limits for EMF for frequencies
  ranging up to 300 GHz
• These limits are based on the ICNIRP
  Guidelines(ICNIRP International Commission on
  Non Ionizing Radiation Protection) which
  considered short term effects (such as dizziness,
  peripheral nerve stimulation, temperature
  effects.) reported at fields levels not used in
  MRI.
• Peripheral nerve stimulation is not considered by
  ICNIRP for workers. The ICNIRP limit in the kHz
  range is based on effects ion the central nervous
  system
• An explicit statement in the directive states
  that long term effects are excluded from the
  scope of the directive (e.g. carcinogenic
  effects...) and hence the directive applies only
  to acute effects.

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The EMF Directive

• Limit values are based on possible short term
  health effects. According to the WHO definition,
  this includes negative effects on personal
  well-being.
• In any event, workers shall not be exposed above
  the limit values.
• Using the precautionary principle, these
  exposure limits are far below those which may
  produce known physiological effects and those
  applied to patients.
• ? Result a severe conflict with the application
  of MR

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Limit values and action values

• For the whole frequency range exposure limit
  values and action values are defined
• Limit values are quantities which are directly
  related to biological considerations
• up to 10 MHz induced body current density in
  A/m2
• above 10 MHz Specific Absorptions Rate (SAR) in
  W/kg
• However, these quantities are difficult to
  measure and action values are defined for
  practical exposure assessment
• Action values are derived from the limit
  values in terms of E-field (V/m) or magnetic
  flux density (T)
• Under the directive it will not be allowed to
  exceed limit values.
• Compliance with action values implies compliance
  with the relevant
• exposure limit values.

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In the workplace
The Directive applies in the same way to all
workplaces with no special provision or exemption
for the medical environment.
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Exposure limit values in the EMF Directive
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Exposure action valuesin the EMF Directive
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What current MRI safeguards exist?
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The MR safety standard is IEC 6061-2-33
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Limit values in International Safety Standard IEC
60601-2-33 ()

• EMF Directive for occupational health and safety
  defines exposure limits and action values for
• Personnel in hospitals, practice (radiologist,
  technician)
• Employers of the MR manufacturers (RD,
  installation, service)
• The MR standard IEC 60601-2-33 defines exposure
  limits for safety of patients such as
• Static magnetic field (prevention of nausea,
  dizziness)
• Gradient fields (prevention of peripheral nerve
  stimulation)
• RF field (prevention of body heating)
• () note IEC 60601-2-33 Particular requirement
  for the safety of magnetic resonance equipment
  for medical diagnostic. This standard has been
  written and maintained by the IEC group MT40,
  consisting of experts from MR users and
  researchers, regulatory bodies and MR
  manufacturers

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Progress on IEC 60601-2-33

• IEC MT 40 is currently working on a 2nd amendment
  to the IEC 60601-2-33, which specifically
  addresses EMF exposure for MR workers. There
  proposals are
• Static magnetic field proposed limit value is
  equal to the value for the patient (4T) and
  working at higher field strength is subject to
  approval from local ethics commission
• Gradients Proposed limit value is equal to the
  the value for the patient, which is based on the
  level required to produce peripheral nerve
  stimulation. No peripheral nerve stimulation will
  be observed by the MR worker. Unless he is
  bending into the scanner
• SAR the proposed values for workers are equal to
  the values for the patient (and thus the whole
  body SAR 4W/kg estimated to result in a core
  temperature increase of max. 10 C). But that is
  if the worker would be inside the transmit coil
• Status 2nd amendment distributed as Committee
  Draft for Vote result due Nov/2006

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Conflicts between the EMF directive and
scientific opinion
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Bodies expressing concernand their relevant
actions

• Intensive discussion have started at Europe and
  national level, e.g. the UK House of Commons
  select-committee report Watching the Directives
  Scientific Advice on the EU Physical Agents
  (Electromagnetic Fields) Directive which is very
  critical, and activities in France, Finland,
  Germany, Netherlands
• ISMRM / ESMRMB Activities of the Safety
  Committees,
• publishing of information on their websites
• promotion of scientific work on MR
• COCIR
• determining a common strategy for MR
  manufacturers
• comments submitted to European Commission
• participating in a COCIR Task Force on the
  practical
• implementation of the EC Directive
• IEC MT40
• writing an amendment to the MR safety standard
  IEC 60601-2-33 for the safety of MR workers by
  defining exposure limit values (which are
  different to those from the current EC
  Directive)

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Specific areas of conflict

• The MR community sees a conflict with ICNIRP for
  all 3 EMF regions for MR
• Static magnetic field limit value must be
  expressed as T/s and not as T
• Gradients Peripheral Nerve Stimulation is the
  limiting physiological process and not visual
  phosphenes as used by ICIRP
• SAR the proposed values for workers are
  over-conservative
• ICNIRP has acknowledged that the limits proposed
  are for workers in general, not taking into
  account any social and economical considerations.
  
• A risk benefit analysis should be undertaken in
  light of the undue conservatism used by ICNIRP.
• MRI scanners fulfil the requirements as specified
  for patients for all 3 types of EMFs and are CE
  marked. Changing the specification of the MR
  scanner for Europe is therefore not considered
  because it would deny optimal diagnostic
  capabilities for the patient.

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Limit values in the Directive compared to the MR
safety international standard IEC 60601-2-33 and
our view on them
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Typical MRI magnets
Open Magnet
Cylindrical Magnet
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200 mT area
stray field of a typical 1.5 T magnet
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• Limitations imposed by the EMF directive-
• Currently NO limitation, because no limit value
  is defined!! Definition of limit value could be
  prevented
• (draft proposal was 2 T peak, 200 mT averaged
  over 8 hours)
• However, 12 If the European Commission has to
  close this gap (2009) then problems may occur
• Working on high field systems (peak value)
• Working on medium field systems (average value)

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• Limitations imposed by the EMF directive-
• In order to to stay below 40 mA/m2 personnel
  entering the magnet room for patient positioning
  or system maintenance will have to
• reduce speed of movement to less than 0.10 m/s _at_
  3 T
• reduce speed of movement to less than 0.25 m/s _at_
  1.5 T
• go back to the MR stone age (i.e. low field MR
  _at_ 0.5 T or less)

• Publication by Crozier, Liu Numerical
  evaluation of the fields induced by body motion
  in or near high-field MRI scanners indicates
• up to 300 mA/m2 induced _at_ 1 m/s in stray field of
  3 T magnet
• up to 120 mA/m2 induced _at_ 1 m/s in stray field of
  1.5 T magnet

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• Limitations imposed by the EMF directive-
• Limits may exceeded by people inside the
  examination room during a scan (anesthesiologists,
  assistant scanning children, service
  technician) procedures requiring these people
  cannot be undertaken.
• Interventional MR exposure levels for doctors
  can be as high as those for patients (at least
  the partial body exposure) therefor such
  procedures cannot be carried out.
• Scanning of volunteers?

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Examples of negative impact of the EMF directive
on MRI and the applications at risk
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Typical MR operating parameters

• Static magnet field
• clinical routine 0.2 T 3 T
• clinical research 3 T 7 T ( 9 T)
• Gradients
• dB/dt 50 T/s (ca. 10 mT in 200 msec)
• Slew Rate 200 T/m /sec
• Limited to prevent peripheral nerve stimulation
• RF
• SAR up to 4 W/kg
• Limited to cause body core temperature rise lt 1
  0C

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How do these operating Parameters relate to the
EMF directive?

• Static magnetic fields
• Not covered no Limit value defined
• However, moving faster than about 0.2m/s in the
  static field probably causes induced currents
  which exceed exposure levels
• Gradient fields
• Workers must not be in fields greater than 30mT.
• SAR
• Workers must not exceed 0.4 w/kg whole body
  average.

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Applications at risk

• Emergency cases (e.g. coma patients)
• Special populations (e.g. babies)
• Interventional applications
• Research and innovation in Europe (e.g. MR PET)
• These result from the exposure limits for SAR and
  currents induced by changing magnetic fields
• All applications of MR are no longer possible....
• ....if currents induced by movement in the static
  field are not excluded!

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ApplicationsInterventional MR
(Details in separate file)
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COCIR statements and recommendations
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COCIR Questions

• EC directives noise and vibration contain a
  chapter derogations.
• Why are we told derogations are not possible
  for the EMF directive for medical uses where an
  existing International Standard exists?
• The directive only applies to acute effects.
• Why are workers treated differently to patients?
• IEC 60601-2-33 (Particular requirement for the
  safety of magnetic resonance equipment for
  medical diagnostic) is a perfect candidate to
  assure safety in the MRI environment.
• Why is this not being used?
• The exposure level for the MR worker close to the
  edge of the bore of the system both for the RF
  and the gradients is difficult to measure and
  must therefore be estimated based on simulations.
  
• Do we need more research in this area?

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Consequences of the implementation of the EMF
directive

• If partially implemented i.e. the effects of
  moving in a magnetic field are ignored, then many
  existing and developing applications will be
  prevented.
• If the directive is implemented as published,
  then MRI will be unusable.

In each case, the treatment of patients will be
compromised due to the lack of diagnostic
imaging, or they will be subjected to unnecessary
exposure to ionising radiation.
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COCIR Recommendations

• A general exemption from the scope of the EMF
  Directive for personnel working in
  electromagnetic fields in connection with the use
  of MR is enacted and the International Safety
  standard, specifically designed for MRI, is
  adopted.
• Research is undertaken to establish the real
  consequences of exposure to EMF at the levels
  used in MRI, and a risk benefit analysis is then
  undertaken.

( IEC 60601-2-33)
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However,

• MR services are among the most powerful, yet
  safest, of all diagnostic procedures to be
  developed in the history of modern medicine
• (Emanuel Kanal)