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Control measure

Safe system of work: MRI scanner

Control measure knowledge

If the MRI (magnetic resonance imaging) scanner is still emitting a strong magnetic field,  personnel should not enter the scanner room (beyond the demarcation line) with any metal or battery operated objects.

As the Faraday cage around an MRI scanner blocks normal communication equipment, it may be necessary to implement line of sight communications or to physically relay messages.

It may be necessary to use atmospheric monitoring to identify if cryogenic gases have leaked from the scanner into surrounding rooms. If gases are identified, respiratory protective equipment (RPE) should be worn and the safety of deploying personnel into a room containing cryogenic gases should be considered. For more information see Personal protective equipment (PPE): Cryogenic materials.

Isolating an MRI scanner

Isolating the power supply to an MRI scanner will not stop the strong magnetic field being generated. However, there may be some incidents, for example if the scanner is involved in fire, where isolating the power supply would be necessary.

Wherever possible this should be done by the scanner operator, but electricity can be isolated by fire and rescue service personnel if it is not safe for the operator.

Refer to the hazard of On-site machinery and the control measure Isolate power supplies for on-site machinery.

MRI scanner emergency shutdown procedure

In the event of fire or entrapment, for example if somebody becomes trapped in the magnetic field because they are holding or wearing a metallic item, the operators of the MRI scanner are trained to perform an emergency shutdown (quench) of the scanner.

To shut down the magnetic field, the scanner is quenched of cryogenic liquids. This task will take several minutes, during which time a high strong magnetic field will still exist.

Taking this course of action should only be done when there is a  threat to life risk due to the high financial cost. Quenching has the potential to damage the scanner. Once quenched, the scanner cannot be restarted without specialist engineers replenishing the cryogenic liquids and resetting the equipment.

Strategic actions

Fire and rescue services should:
  • Ensure information about MRI scanners, their location and their emergency shutdown procedures is recorded in Site-Specific Risk Information (SSRI)
  • Maintain contact details for specialist advice for MRI scanners

  • Inform their personnel about the hazard of exposure to strong magnetic fields if they have any metal implants or fragments

Tactical actions

Incident commanders should:
  • Ensure fire and rescue service personnel are made aware of the strong magnetic field
  • Not deploy any metallic equipment into the scanner room (beyond the demarcation line) unless the magnetic field has been shut down
  • Liaise with the MRI operator to identify appropriate actions

  • Consider requesting an emergency shutdown of the MRI scanner, if there is a threat to life, taking into account the consequences of this action

  • Ensure personnel entering the hazard area do not have any metal implants or fragments that may be affected by the strong magnetic field

  • Be aware of the impact of MRI scanners on communication equipment

  • Implement alternative communication methods when MRI scanners affect radio transmission

  • Ensure cryogenic gases have not leaked into the scanner room prior to committing fire and rescue service personnel

  • Ensure any fire and rescue service personnel committed into the scanner room where there may be a hazard of asphyxiation wear appropriate respiratory protective equipment (RPE)
  • Consider requesting the MRI operator to isolate the scanner