FD MRI Safety

Fire Department MRI Safety

THE MAGNET IS ALWAYS ON!

Bed ~ 300 lbs

Solution

Problem

Take direction from the hospital team. Use the reach of the stream when an MRI area is involved in significant fire. Stay outside Zone 3 until the magent has been "Quenched"

An MRI with an active magnet poses a high risk to Firefighters based on the equipment we utilize and our gear being filled with metal objects.

ALERT

+ info

Quenching the Magnet

~ 12,000

US MRI Systems IN use

480 Volts

Electrical load coming into MRI Equipment room

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~ 1000 Liters

Fire Department Operations

The MRI environment is divided in 4 distinct, clearly labeled zones which allow for control of access of people in the MRI setting.

Liquid Helium for Cooling

Zones of MRI Safety

Fire Supression

Metal Results in Inury

Zone Info

INVESTIGation

4 Zones

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name@mail.com

Magnetic Resonance Imaging Safety for Firefighters by Craig Jones Fire Engineering Magazine

Fortunately, there are only a few stories of firefighters injured by MRI machines. The only current documented story I have heard is of a firefighter in Freiburg, Germany, who was called to the MRI suite in which the operator’s computer console had short-circuited and produced smoke. Responders requested that the staff leave the room. One firefighter was assigned to check out the room containing the MRI. He was wearing SCBA and was drawn into the MRI machine’s opening (called the bore). A news report said that he had been folded in half, with his knees pressed into his chest, and nearly choked to death. MRI staff had to quench (shut down) the magnet to extricate him.

Not our typical "entrapment".

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Any metal or ferous objects should not be with in the Zone 3 area:

This includes items such as:

• Nozzles
• Hose
• Fire Extiguishers
• Hand Tolls
• SCBA
• Radios
• Keys
• Coat Buckles

Things that you have inside you also need to be considered:

• Pacemaker
• Nuerostimulator
• Internal defribrillator
• Cochlear implants (hearing aids)
• Clamps
• Other objects: bullets, shrapnel

MRI Safe Fire Extinguisher

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• Quenching reduces the machine’s magnetic pull to 0 G and is manual or spontaneous. For every MRI machine, there is at least one button/plunger to manually quench the magnet. It may be found in the operator’s room or in the magnet room. It is typically a plunger-style button and red (although it could be any color).
• A quench (manual or spontaneous) takes about a minute and results from the loss of the helium. There may be no noise, or you might hear gas venting to the outside. The helium does not escape into the magnet room, so there is no hazard associated with a quench. You cannot see a magnetic quench except for the plume of helium venting through the piping in the roof. The plume can be quite large, since liquid helium will expand 754 times its volume when it becomes gaseous. When a spontaneous quench (an automatic quench typically resulting from an unsafe condition) occurred at our facility, people outside saw the plume of helium venting from the roof, thought it was a fire, and called the fire department.For a manual quench, you just have to push the quench button. The helium that keeps the magnet supercooled escapes, and the resistance in the wires increases significantly. The lack of supercooling and increased resistance decrease the electricity going through the wires, therefore decreasing the magnetic field. Several thousand liters of expensive helium are used to cool the wires, so refilling a quenched magnet can cost a minimum of between $10,000 and $20,000.
• A second consideration when quenching an MRI machine is that when the helium vents, the wires heat up quickly. If they heat up too quickly, they can melt together, rendering the magnet unusable. So, quench a magnet only in life-threatening situations.

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• A magnet’s field strength is measured in gauss (G) or Tesla (T) units. One T is 10,000 G. The earth’s magnetic field is approximately 0.5 G (0.00005 T). Typically, a hospital MRI machine’s magnet will have a field strength of between 1.5 and 3 T, measured at the center (inside) of the magnet. In comparison, a large electromagnet on a crane used to move scrap cars around a junkyard, when on, is approximately 1.5 T. So, the MRI magnet is very powerful. But note that the scrap yard electromagnet can be turned on and off, whereas the MRI machine in a hospital is always on!

• MRI machines in hospitals usually contain some other technology to contain this 5-G boundary to within the magnet room while maintaining the full field strength at the center of the magnet. Active shielding technology is used to reduce the magnetic field outside of the magnet.

• The active shielding can reduce the distance of 5-G boundary from dozens of meters away to between two and five meters around a machine. Although most hospital-based MRI machines have active shielding, some MRI machines in research environments may not.

• This information is important for our operations due the signifigance of wall degradion or demoltion during fire operations.

Overhaul may be difficult in lined walls

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Fire Suppression Considerations

The room is constructed with very specific considerations for the machine’s weight and the vibrations it creates when in use. Typically, the floor is reinforced with concrete, since an MRI machine weighs between five and 10 tons. The door usually contains copper to prevent stray radio frequencies from intruding. In rare cases, the walls may contain steel to reduce the magnetic field outside or copper caging to reduce radio frequency transmission into the room. These modifications present potential problems in a large fire that necessitates ventilation. A metal detector should not replace common sense.

If there is a fire in the magnet room, you must judge the size of the fire and the resources available. One rule of thumb is that if the fire is the size of a basketball or smaller, use the nonmetallic fire extinguisher to put the fire out. Obviously, you could try other means, too (e.g., smother). If the fire is larger and requires more extinguishers or a fire hose, then quench the magnet. While waiting for the all clear utilize the reach of the hose stream from outside Zone 3.

While waiting for the all clear utilize the reach of the hose stream from outside Zone 3 Think like your making a Blitz Attack or Staying out of the collapse zone.

Feed the sprinkle system, it can have a significant impact on fire spread while you are at a safe distance.

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Fire Investigation Considerations

The room is constructed with very specific considerations for the machine’s weight and the vibrations it creates when in use. Typically, the floor is reinforced with concrete, since an MRI machine weighs between five and 10 tons. The door usually contains copper to prevent stray radio frequencies from intruding. In rare cases, the walls may contain steel to reduce the magnetic field outside or copper caging to reduce radio frequency transmission into the room. These modifications present potential problems in a large fire that necessitates ventilation. A metal detector should not replace common sense.

If there is an alarm in the MRI utilize the hospital team to assist in your investigation. Tools such as Thermal Imaging can be utilized from a distance. Nearly all MRI units have a control room with a window where you can look into the room for tripped heads or other issues.

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