MRSO FULL QUESTIONS AND CORRECT
ANSWERS PROFESSIONAL PREPARATION
MATERIAL
●● Quench
Answer: Quickly eliminating the magnetic field.
Not immediate, takes 3 to 5 minutes to completely eliminate magnetic
field.
Loud Noise as Helium rushes out of Quench Vent.
Can cause crack in the wire (very costly to repair/replace).
●● Ohm's Law
Answer: Resistance that is equal to Voltage divided by the amperage in a
wire.
V=IR
Use of Cryogen reduces/eliminates heating with high voltage and
amperage which allows for high magnetic field.
,●● Cryogen
Answer: Liquid Helium
42* Kelvin
●● Dual Cryogen System
Answer: Helium
Nitrogen (used to keep Helium cold as back-up)
●● Quench Vent
Answer: Used to vent boiled off Helium to the outside.
Quench Vent in MRI Room is Zone IV (MRI manufacturer/engineer
responsible for inspecting)
Quench Vent outside is Zone III (Facility responsible for inspecting)
●● Quench concerns with malfunctioning Quench Vent.
Answer: Dense fog in room.
,Can rain or snow which can contain Oxygen which is a fire risk.
Hypothermia/Frostbite due to lowered room temperature.
Aphyxiation
Ruptured Ear Drums because of increased pressure in room.
Difficulty opening door to Zone III due to increased pressure. May have
to break window to release pressure.
Magnet doesn't immediately lose its magnetic field.
Peripheral Nerve stimulation due to change in magnetic field.
●● Static Magnetic Field Concerns
Answer: Translation/Rotational Force
*No adverse effects to patients or fetus have been noted to individuals
exposed to up to 8T.
●● Static Magnetic Field Occupational Exposure Limits
Answer: ICNIRP
, - Head and trunk is limited to a magnetic flux
density of 2T
- Limits are limited to a magnetic flux density of
8T
IEC
- Head and trunk is limited to a magnetic flux
density of 4T.
- Limbs are limited to a magnetic flux density of
4T.
●● Static Magnetic Field General Public Exposure Limits
Answer: 400mT
●● FDA Limits for Static Magnetic Field
Answer: < 1 month old - 4T
>1 month old - 8T
ANSWERS PROFESSIONAL PREPARATION
MATERIAL
●● Quench
Answer: Quickly eliminating the magnetic field.
Not immediate, takes 3 to 5 minutes to completely eliminate magnetic
field.
Loud Noise as Helium rushes out of Quench Vent.
Can cause crack in the wire (very costly to repair/replace).
●● Ohm's Law
Answer: Resistance that is equal to Voltage divided by the amperage in a
wire.
V=IR
Use of Cryogen reduces/eliminates heating with high voltage and
amperage which allows for high magnetic field.
,●● Cryogen
Answer: Liquid Helium
42* Kelvin
●● Dual Cryogen System
Answer: Helium
Nitrogen (used to keep Helium cold as back-up)
●● Quench Vent
Answer: Used to vent boiled off Helium to the outside.
Quench Vent in MRI Room is Zone IV (MRI manufacturer/engineer
responsible for inspecting)
Quench Vent outside is Zone III (Facility responsible for inspecting)
●● Quench concerns with malfunctioning Quench Vent.
Answer: Dense fog in room.
,Can rain or snow which can contain Oxygen which is a fire risk.
Hypothermia/Frostbite due to lowered room temperature.
Aphyxiation
Ruptured Ear Drums because of increased pressure in room.
Difficulty opening door to Zone III due to increased pressure. May have
to break window to release pressure.
Magnet doesn't immediately lose its magnetic field.
Peripheral Nerve stimulation due to change in magnetic field.
●● Static Magnetic Field Concerns
Answer: Translation/Rotational Force
*No adverse effects to patients or fetus have been noted to individuals
exposed to up to 8T.
●● Static Magnetic Field Occupational Exposure Limits
Answer: ICNIRP
, - Head and trunk is limited to a magnetic flux
density of 2T
- Limits are limited to a magnetic flux density of
8T
IEC
- Head and trunk is limited to a magnetic flux
density of 4T.
- Limbs are limited to a magnetic flux density of
4T.
●● Static Magnetic Field General Public Exposure Limits
Answer: 400mT
●● FDA Limits for Static Magnetic Field
Answer: < 1 month old - 4T
>1 month old - 8T
