MAGNETIC RESONANCE SAFETY
EXPERT (MRSE) – EXAM QUESTIONS &
VERIFIED ANSWERS 2026/2027 UPDATE
1. Which physical phenomenon is primarily responsible for the rotational force experienced
by a non-spherical ferromagnetic object when placed in a static magnetic field?
A. Magnetic torque
B. Translational attraction
C. Lenz’s Law
D. Lorentz force
Answer: A
Conceptual Explanation: Magnetic torque (N = m x B) occurs when the magnetic moment
of an object is not aligned with the static magnetic field (B0), attempting to align the
object’s long axis with the field lines.
2. According to IEC 60601-2-33, what is the whole-body SAR limit for the ‘Normal Operating
Mode’ over a 6-minute period?
A. 1.0 W/kg
,B. 8.0 W/kg
C. 4.0 W/kg
D. 2.0 W/kg
Answer: D
Conceptual Explanation: The Normal Operating Mode limit for whole-body SAR is 2.0
W/kg. The First Level Controlled Mode increases this limit to 4.0 W/kg.
3. An MR Conditional implant specifies a maximum spatial field gradient of 20 T/m (2000
G/cm). If the magnet’s peak spatial gradient is located 50 cm from the isocenter, what risk is
most concerning if this limit is exceeded?
A. Unintended movement due to translational force
B. Vibration due to Lorentz forces
C. Resonant RF heating
D. Malfunction of internal electronics
Answer: A
Conceptual Explanation: Spatial field gradient (dB/dx) is the primary determinant of the
translational (attractive) force acting on an object. Exceeding the rated T/m limit risks
displacement of the implant.
4. Which of the following describes the ‘Antenna Effect’ in MR safety?
A. The concentration of RF energy at the tips of long conductive leads
, B. The ability of the gradient coils to pick up radio signals
C. The broadcasting of noise from the cold head
D. The reflection of B0 field lines at the room shield
Answer: A
Conceptual Explanation: The antenna effect occurs when the length of a conductive lead
(like a pacemaker wire) is a fraction of the RF wavelength, leading to standing waves and
intense heating at the tips.
5. During a quench, why is it critical to evacuate the room immediately even if the cryogen
vent appears to be working?
A. The magnetic field increases rapidly during a quench
B. Risk of structural collapse from pressure
C. Potential oxygen displacement and asphyxiation
D. Extreme RF exposure from the collapsing field
Answer: C
Conceptual Explanation: A quench involves the rapid boil-off of liquid helium. If the vent
fails or leaks, helium gas displaces oxygen, leading to rapid asphyxiation and pressure
build-up that may jam doors.
EXPERT (MRSE) – EXAM QUESTIONS &
VERIFIED ANSWERS 2026/2027 UPDATE
1. Which physical phenomenon is primarily responsible for the rotational force experienced
by a non-spherical ferromagnetic object when placed in a static magnetic field?
A. Magnetic torque
B. Translational attraction
C. Lenz’s Law
D. Lorentz force
Answer: A
Conceptual Explanation: Magnetic torque (N = m x B) occurs when the magnetic moment
of an object is not aligned with the static magnetic field (B0), attempting to align the
object’s long axis with the field lines.
2. According to IEC 60601-2-33, what is the whole-body SAR limit for the ‘Normal Operating
Mode’ over a 6-minute period?
A. 1.0 W/kg
,B. 8.0 W/kg
C. 4.0 W/kg
D. 2.0 W/kg
Answer: D
Conceptual Explanation: The Normal Operating Mode limit for whole-body SAR is 2.0
W/kg. The First Level Controlled Mode increases this limit to 4.0 W/kg.
3. An MR Conditional implant specifies a maximum spatial field gradient of 20 T/m (2000
G/cm). If the magnet’s peak spatial gradient is located 50 cm from the isocenter, what risk is
most concerning if this limit is exceeded?
A. Unintended movement due to translational force
B. Vibration due to Lorentz forces
C. Resonant RF heating
D. Malfunction of internal electronics
Answer: A
Conceptual Explanation: Spatial field gradient (dB/dx) is the primary determinant of the
translational (attractive) force acting on an object. Exceeding the rated T/m limit risks
displacement of the implant.
4. Which of the following describes the ‘Antenna Effect’ in MR safety?
A. The concentration of RF energy at the tips of long conductive leads
, B. The ability of the gradient coils to pick up radio signals
C. The broadcasting of noise from the cold head
D. The reflection of B0 field lines at the room shield
Answer: A
Conceptual Explanation: The antenna effect occurs when the length of a conductive lead
(like a pacemaker wire) is a fraction of the RF wavelength, leading to standing waves and
intense heating at the tips.
5. During a quench, why is it critical to evacuate the room immediately even if the cryogen
vent appears to be working?
A. The magnetic field increases rapidly during a quench
B. Risk of structural collapse from pressure
C. Potential oxygen displacement and asphyxiation
D. Extreme RF exposure from the collapsing field
Answer: C
Conceptual Explanation: A quench involves the rapid boil-off of liquid helium. If the vent
fails or leaks, helium gas displaces oxygen, leading to rapid asphyxiation and pressure
build-up that may jam doors.
