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MRI Facility design (MRI specific)

 

MRI facilities are designed and constructed in a manner that minimizes safety risks

 

+ Importance of controlling access to the MRI environment

  • The MRI environment has specific safety concerns related to the static magnetic field:
    • Medical devices may malfunction within the static magnetic field, placing individuals with these devices at risk for serious or fatal injury1
    • Other ferromagnetic items inadvertently taken into the static magnetic field pose a projectile risk and have been known to cause fatal trauma to patients, staff and others1,2

 

  • In addition to the static field, MRI systems use large liquid helium reserves which, if accidentally released, pose a hazard to those in the vicinity (i.e., potential for asphyxiation and cryogen burns).2
    • MRI system quenches can be dangerous for individuals unaware of the associated risks and the required emergency procedures within the MRI environment

 

  • Controlling access to the MRI environment is instrumental in:1,2
    • Preventing accidents and reducing risk for serious or fatal injury
    • Ensuring medical devices and MRI scanning systems are not damaged and/or rendered useless
    • Mitigating system downtime and maintaining a safe and effective working environment

+ Zones

  • A four zone facility design is used to control and restrict access to the MRI environment.2
  • The facility is conceptually divided into zones that physically restrict access of health care personnel into areas of danger due to proximity to the static magnetic field:2
    • Zone I – Access to general public for example reception or waiting areas
    • Zone II – Access to unscreened individuals; for example, change and preparation areas
    • Zone III – Physically restricted barrier and consists of areas that have immediate access to the magnet room for example the control room
    • Zone IV – Physically confines the magnet room or areas where the 5 gauss fringe field extends

+ Restricting access

  • Entry to zone III and beyond is authorized ONLY by level 2 personnel*.
    • All individuals entering zone III are under direct supervision of level 2 MRI personnel

 

  • Zones III and IV are locked down when not under direct supervision of level 2 personnel.
    • This restriction is ensured by a physical barrier that is unlocked by key or badge pass
    • Combination locks should not be used, because of the risk a combination could be disseminated to other non-MRI personnel


* Level 2 MRI personnel are defined as those with MRI safety education to ensure safety of all individuals and facility resources within the MRI environment

+ Signage

  • Clear and explicit signage is important to reinforce the safety features of the four-zone design.1,2
  • Recommended signage includes:
    • Clear and permanent demarcation of the 5 Gauss line on the floor in the magnet room
    • Prominent danger signs on the magnet room doors (e.g., “Danger due to the presence of a Strong Magnetic Field, Do not Enter, No Ferromagnetic Objects”)
    • Prominent signage and indicators that indicate the magnet is always on (e.g., a light that is lit at all times, running on back-up power source, accompanied by a sign above or beside door stating “The magnet is Always On”)
    • Signage indicating-MRI zones
    • Zone III and IV require signage which indicates the zone and the restricted access level

+ General design elements

  • MRI environments are designed to facilitate MRT supervision of Zone IV access from the standard working position at the console.
    • This environment is difficult to supervise and increase the risk of a safety incident
    • Multiple entrances to zone IV are discouraged

 

  • MRI environments are designed to encourage quality patient care:
    • MRTs are able to directly monitor and visualize patients in the magnet bore
    • MRTs are able to hear patients between scans (consideration of types of material used in construction and background noise levels in control room)

 

  • Patient confidentiality is considered by restricting line of sight of patient information on computer screens or desks.

+ References

  1. Shellock FG. Reference Manual for Magnetic Resonance Safety, Implants, and Devices. 2012 Ed. Los Angeles, CA: Biomedical Research Publishing Group; 2012.
  2. Kanal E, et al. American College of Radiology White Paper on MRI safety. AJR 2007;188:1-27.

 

Validation

May 8, 2013

 

 
Canadian Association of Medical Radiation Technologists
85 Albert St, Suite 1000, Ottawa, ON, K1P 6A4
phone: 613 234-0012 / 800 463-9729
fax: 613 234-1097
www.camrt.ca