MRI Safety policy

Incidental hazards to Operators and patients in a restricted access area

Safety Precautions in the MRI suite


This document is intended to be a brief description of the safety precautions in the MRI suite and is updated as needed.

The 1988 FDA Guidance and Safety Parameter Action Levels indicate that static field strengths of up to 2 Tesla comprise non-significant risk to humans. In 1996/7 the FDA concludes that static field strengths of 4 Tesla or lower are not considered significant risk. More recently, the FDA has approved research systems with field strengths up to 8 Tesla (~2000). Field strength of 3 Tesla has also been approved by the FDA for routine clinical use (~2000). However, it is recommended that small children and pregnant women minimize exposure to high magnetic fields as the long term-effects are unknown. If you need more information please drop by our office.

Access to the MRI scanners is restricted and strictly enforced. There are a few precautions when working with high magnetic fields. You and your PI need to sign a form (below) acknowledging that you understand the safety precautions and that you are properly trained before you can operate the scanners or participate in MRI studies. Major precautions are described below.

Under no circumstance can ANY MAGNETIC METAL be bought into the magnet rooms. If you are not sure, do not bring them in the magnet rooms. Generally, only the animals, cradle and detectors go in the magnet rooms. The cart used to wheel the animals can not go into the magnet room. It is a good practice to remind yourself of this and to empty your pockets before entering the magnet room.

Pace maker and implanted objects: No person with any implanted metal object (pacemaker, prosthesis, pins, clips, IUD’s) is allowed to enter the imaging suite. These implanted objects might dislodge (e.g., an aneurysm clip), malfunction (e.g., a pacemaker) or become attached to the magnet (e.g., a metal pin) in high static magnetic fields causing serious injury or death.

Projectiles and blunt forces: It is possible for a person to become trapped between the cryostat and a magnetic object. If the object is fairly massive (e.g., a pound or more), forces of up to 150 pounds may be generated for every pound of ferromagnetic material. The person may thus be subjected to severe force and mechanical stress. Objects can become projectiles. Compress gas tanks, surgical tools, hardware tools (e.g., screwdrivers) are of common danger. It is important to keep in mind that magnetic force of the magnetic objects grow very rapidly as they get closer to the magnet so it may be too late before you realize its very strong force.

Asphyxiation: The cryostat of the magnet contains several hundred liters of cryogens. If the magnet quenches, (i.e., makes the transition from superconducting to resistively conducting) the liquid helium in the innermost cryostat will boil off rapidly, and may displace oxygen in a closed environment, leading to an asphyxiation hazard. In our facility, the helium vapor is directly vented to outside the building in case of a quench so asphyxiation hazard only happens if the vent malfunctions.

In case of fire: Follow Yerkes’ SOP. In addition, operators and trained personnel need to direct firefighting operation (when safely to do so). Advise firefighters/policemen and other emergency workers NOT to go into the magnet rooms with their equipment. This will cause bodily injury and damage to equipment. Fire extinguishers cannot go inside the magnet rooms.

SIGNS AND WARNINGS are posed at entrances to the magnet rooms warning of high magnetic field hazards. Again people with implanted objects (e.g., pacemakers) are NOT allowed into the imaging suite. High magnetic field will affect pacemakers, beepers, watches, credit cards and electronic equipment. Iron and steel can be pulled into the magnet. No person with any implanted metal object (pacemaker, prosthesis, pins, clips, IUDs) will be allowed to enter.

Quench button: The quench button is used to quench the magnet ONLY in case of MEDICAL EMERGENCY (e.g., a person’s life is in danger). Please contact an MR staff otherwise. The quench button (red) is located in the magnet room and/or the equipment room.

Housekeeping staff cannot go into the magnet rooms.

Visitors: If you bring visitors and collaborators into the MRI suite, you will be completely responsible for them, including their safety. Your collaborators also need to sign the same form (below). No visitors are allowed in the magnet rooms.


Follow Yerkes SOP for reporting all safety incidents. In addition, also report all incidents to our office (see contact) immediately. These incidents may be referred to the internal MRI Advisory Committee, which will take appropriate action as needed. Examples are, but not limited to,

  1. Incidents in which any person was injured.

  2. Incidents requiring the emergency quench of the magnet.

  3. Incidents involving damage to equipment.

  4. Conditions which constituted a safety hazard.

  5. Incidents in which approved protocols were not followed, causing an unsafe condition


Active IACUC protocols on file with us are needed to perform experiments at the Yerkes Imaging Center. Please give us a copy of your IACUC approval letter. Violation of IACUC protocols will be referred directly to the IACUC committee.

For additional information, please do not hesitate to contact our office.


Signing below indicates that you understand the above safety procedures. Give us a copy and keep one for your review/record.

Print Name -------------------- Phone # -------------------- Email -------------------- Signature------------------- Date-------------------

Your PI name -------------------- Phone # -------------------- Email -------------------- Signature --------------------
Date ------------------

Approved by: Name ------------------------- Signature ------------------------ Date ----------------------


Only certified personnel can operate the scanners independently.

To become certified, you must attend hand-on training session and perform MRI experiments with an MR staff for at least 40 hours.
To get training, contact our office (a typical training will involve MR safety, shadowing on experiments and performing experiment).

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