MAGNETIC RESONANCE SAFETY EXPERT (MRSE) EXAM
QUESTIONS AND LL ANSWERS CORRECT (PASS
GUARANTEE) LATEST VERSION
1. Q: What does MRI stand for? ANSWER Magnetic Resonance Imaging
2. Q: What is the primary magnetic field in MRI designated as? ANSWER
B₀ (B-zero or static magnetic field)
3. Q: What is the gyromagnetic ratio for hydrogen? ANSWER 42.58
MHz/Tesla
4. Q: What is the Larmor frequency? ANSWER The frequency at which
hydrogen protons precess in a magnetic field, calculated as γ × B₀
5. Q: What causes the RF burn risk in MRI? ANSWER Radiofrequency
energy deposition causing tissue heating through electric field coupling
6. Q: What does SAR stand for? ANSWER Specific Absorption Rate
7. Q: What are the units for SAR? ANSWER Watts per kilogram (W/kg)
8. Q: What is the FDA limit for whole-body averaged SAR? ANSWER 4
W/kg averaged over 15 minutes for normal operating mode
9. Q: What is the typical field strength of a clinical MRI scanner?
ANSWER 1.5 Tesla or 3 Tesla (though ranges from 0.2T to 7T and beyond)
10. Q: What are the three types of magnetic fields in MRI? ANSWER
Static field (B₀), gradient fields, and radiofrequency (RF) fields
11. Q: What is the purpose of gradient coils? ANSWER To spatially encode
the MR signal by creating controlled variations in the magnetic field
12. Q: What is the typical slew rate of gradient systems? ANSWER 100-200
Tesla/meter/second (T/m/s)
,13. Q: What is dB/dt? ANSWER The rate of change of the magnetic field
over time, measured in Tesla/second
14. Q: What physiological effect is associated with rapid gradient
switching? ANSWER Peripheral nerve stimulation (PNS)
15. Q: What is the frequency range of MRI gradient-induced acoustic
noise? ANSWER Primarily 1-4 kHz, with levels reaching 100-130 dB
16. Q: What is the spatial peak SAR limit for the head? ANSWER 3.2
W/kg averaged over 10 grams for normal operating mode
17. Q: What is T1 relaxation? ANSWER Longitudinal or spin-lattice
relaxation - the recovery of magnetization along the main field
18. Q: What is T2 relaxation? ANSWER Transverse or spin-spin relaxation -
the decay of magnetization in the transverse plane
19. Q: What is the primary safety concern with static magnetic fields?
ANSWER Projectile (missile) effect from ferromagnetic objects
20. Q: What force attracts ferromagnetic objects to the magnet? ANSWER
Translational force (spatial gradient force)
21. Q: What is magnetic torque? ANSWER The rotational force on
ferromagnetic objects attempting to align with the magnetic field
22. Q: At what field strength does the 5 gauss line become a safety concern?
ANSWER All field strengths, but particularly 1.5T and above where it extends
further from the bore
23. Q: What is the typical strength of Earth's magnetic field? ANSWER
Approximately 0.5 gauss or 50 microtesla
24. Q: What is quenching? ANSWER The rapid boil-off of liquid helium
when a superconducting magnet loses superconductivity
25. Q: What gas is released during a magnet quench? ANSWER Helium
gas (from boiled liquid helium)
26. Q: What is the danger of helium gas in the scan room during a quench?
ANSWER Asphyxiation due to oxygen displacement
27. Q: What is the Faraday cage in MRI? ANSWER RF shielding that
prevents external RF signals from entering and internal RF from escaping
, 28. Q: What is a Tesla? ANSWER The SI unit of magnetic flux density (1
Tesla = 10,000 gauss)
29. Q: What equation describes the force on a charged particle in a
magnetic field? ANSWER F = qv × B (Lorentz force)
30. Q: What is the relationship between frequency and field strength?
ANSWER Linear relationship defined by the Larmor equation (f = γB₀)
31. Q: What is the purpose of shimming? ANSWER To improve magnetic
field homogeneity
32. Q: What are the two types of shimming? ANSWER Passive shimming
(metal shims) and active shimming (shim coils with current)
33. Q: What is the quadrature body coil? ANSWER The built-in RF transmit
coil in the scanner bore
34. Q: What is flip angle? ANSWER The angle that the net magnetization
vector is rotated away from the longitudinal axis
35. Q: What is a 90-degree RF pulse? ANSWER An RF pulse that rotates
magnetization completely into the transverse plane
36. Q: What happens to acoustic noise as gradient performance increases?
ANSWER Acoustic noise increases with faster gradient switching and higher
amplitudes
37. Q: What is the typical magnetic field strength of the fringe field at 3-4
meters from a 1.5T scanner? ANSWER Approximately 5 gauss (0.5 mT)
38. Q: What is duty cycle in relation to SAR? ANSWER The percentage of
time the RF transmitter is actively transmitting
39. Q: Why do fast spin echo sequences typically have higher SAR?
ANSWER Multiple 180-degree refocusing pulses increase RF energy
deposition
40. Q: What is the first level controlled operating mode? ANSWER Normal
operating mode - routine scanning with no physiological stress expected
Section 2: MR Safety Zones and Access Control (Questions 41-70)
QUESTIONS AND LL ANSWERS CORRECT (PASS
GUARANTEE) LATEST VERSION
1. Q: What does MRI stand for? ANSWER Magnetic Resonance Imaging
2. Q: What is the primary magnetic field in MRI designated as? ANSWER
B₀ (B-zero or static magnetic field)
3. Q: What is the gyromagnetic ratio for hydrogen? ANSWER 42.58
MHz/Tesla
4. Q: What is the Larmor frequency? ANSWER The frequency at which
hydrogen protons precess in a magnetic field, calculated as γ × B₀
5. Q: What causes the RF burn risk in MRI? ANSWER Radiofrequency
energy deposition causing tissue heating through electric field coupling
6. Q: What does SAR stand for? ANSWER Specific Absorption Rate
7. Q: What are the units for SAR? ANSWER Watts per kilogram (W/kg)
8. Q: What is the FDA limit for whole-body averaged SAR? ANSWER 4
W/kg averaged over 15 minutes for normal operating mode
9. Q: What is the typical field strength of a clinical MRI scanner?
ANSWER 1.5 Tesla or 3 Tesla (though ranges from 0.2T to 7T and beyond)
10. Q: What are the three types of magnetic fields in MRI? ANSWER
Static field (B₀), gradient fields, and radiofrequency (RF) fields
11. Q: What is the purpose of gradient coils? ANSWER To spatially encode
the MR signal by creating controlled variations in the magnetic field
12. Q: What is the typical slew rate of gradient systems? ANSWER 100-200
Tesla/meter/second (T/m/s)
,13. Q: What is dB/dt? ANSWER The rate of change of the magnetic field
over time, measured in Tesla/second
14. Q: What physiological effect is associated with rapid gradient
switching? ANSWER Peripheral nerve stimulation (PNS)
15. Q: What is the frequency range of MRI gradient-induced acoustic
noise? ANSWER Primarily 1-4 kHz, with levels reaching 100-130 dB
16. Q: What is the spatial peak SAR limit for the head? ANSWER 3.2
W/kg averaged over 10 grams for normal operating mode
17. Q: What is T1 relaxation? ANSWER Longitudinal or spin-lattice
relaxation - the recovery of magnetization along the main field
18. Q: What is T2 relaxation? ANSWER Transverse or spin-spin relaxation -
the decay of magnetization in the transverse plane
19. Q: What is the primary safety concern with static magnetic fields?
ANSWER Projectile (missile) effect from ferromagnetic objects
20. Q: What force attracts ferromagnetic objects to the magnet? ANSWER
Translational force (spatial gradient force)
21. Q: What is magnetic torque? ANSWER The rotational force on
ferromagnetic objects attempting to align with the magnetic field
22. Q: At what field strength does the 5 gauss line become a safety concern?
ANSWER All field strengths, but particularly 1.5T and above where it extends
further from the bore
23. Q: What is the typical strength of Earth's magnetic field? ANSWER
Approximately 0.5 gauss or 50 microtesla
24. Q: What is quenching? ANSWER The rapid boil-off of liquid helium
when a superconducting magnet loses superconductivity
25. Q: What gas is released during a magnet quench? ANSWER Helium
gas (from boiled liquid helium)
26. Q: What is the danger of helium gas in the scan room during a quench?
ANSWER Asphyxiation due to oxygen displacement
27. Q: What is the Faraday cage in MRI? ANSWER RF shielding that
prevents external RF signals from entering and internal RF from escaping
, 28. Q: What is a Tesla? ANSWER The SI unit of magnetic flux density (1
Tesla = 10,000 gauss)
29. Q: What equation describes the force on a charged particle in a
magnetic field? ANSWER F = qv × B (Lorentz force)
30. Q: What is the relationship between frequency and field strength?
ANSWER Linear relationship defined by the Larmor equation (f = γB₀)
31. Q: What is the purpose of shimming? ANSWER To improve magnetic
field homogeneity
32. Q: What are the two types of shimming? ANSWER Passive shimming
(metal shims) and active shimming (shim coils with current)
33. Q: What is the quadrature body coil? ANSWER The built-in RF transmit
coil in the scanner bore
34. Q: What is flip angle? ANSWER The angle that the net magnetization
vector is rotated away from the longitudinal axis
35. Q: What is a 90-degree RF pulse? ANSWER An RF pulse that rotates
magnetization completely into the transverse plane
36. Q: What happens to acoustic noise as gradient performance increases?
ANSWER Acoustic noise increases with faster gradient switching and higher
amplitudes
37. Q: What is the typical magnetic field strength of the fringe field at 3-4
meters from a 1.5T scanner? ANSWER Approximately 5 gauss (0.5 mT)
38. Q: What is duty cycle in relation to SAR? ANSWER The percentage of
time the RF transmitter is actively transmitting
39. Q: Why do fast spin echo sequences typically have higher SAR?
ANSWER Multiple 180-degree refocusing pulses increase RF energy
deposition
40. Q: What is the first level controlled operating mode? ANSWER Normal
operating mode - routine scanning with no physiological stress expected
Section 2: MR Safety Zones and Access Control (Questions 41-70)
