EXAM #1 — CLINICAL UNIT 1

Question 1

1. Identify the largest and most powerful magnetic fields used in MRI

Answer 1

a. Primary field (a.k.a. main field or external field)

Question 2

2. Identify the primary hazard associated with the main magnetic field

Answer 2

a. Interaction with metallic objects

Question 3

3. Identify the 3 classifications of metals with respect to magnetism, in order of most affected to least affected

Answer 3

i. Ferromagnetic: strongly affected by magnetic fields
ii. Paramagnetic: weakly affected by magnetic fields
iii. Diamagnetic: weakly opposed by magnetic fields

Question 4

4. Identify the term used to identify the part if the magnetic field that extends beyond the magnet housing

Answer 4

a. Fringe field, follows inverse square law for intensity

Question 5

5. Identify the danger associated with ferromagnetic objects in the magnetic field

Answer 5

a. Become projectiles, ferromagnetic objects can also be dangerous because they will accelerate toward the magnet at greater speeds than large objects (become projectiles) via attraction

Question 6

6. Identify the term used to describe a paramagnetic object being moved by the magnetic field

Answer 6

a. Deflection, rather than being attracted to the magnetic field, it is said that paramagnetic objects are deflected by the field (turning and twisting)

Question 7

7. Identify areas of the body where metallic foreign bodies are most dangerous when exposed to the main magnetic field

Answer 7

a. Brain, eyes, heart, major arteries, veins, or nerves

Question 8

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   a. Cardiac pacemakers

Answer 8

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   a. Cardiac pacemakers
   i. Not safe (deflection, induction of electrical currents, implant malfunction)

Question 9

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   b. Prosthetic heart valves

Answer 9

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   b. Prosthetic heart valves
   i. Safe

Question 10

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   c. Surgical clips in the chest, abdomen, or pelvis

Answer 10

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   c. Surgical clips in the chest, abdomen, or pelvis
   i. Safe

Question 11

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   d. Vascular clips in the brain

Answer 11

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   d. Vascular clips in the brain
   i. Safe but older models will deflect

Question 12

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   e. Intravascular coils, filters, and stents

Answer 12

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   e. Intravascular coils, filters, and stents
   i. Safe

Question 13

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   f. Metal that is fixed to a bone

Answer 13

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   f. Metal that is fixed to a bone
   i. Safe

Question 14

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   g. Internal cardiac pacemakers

Answer 14

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   g. Internal cardiac pacemakers
   i. Not safe (induction of electrical current, implant malfunction)

Question 15

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   h. Internal neurostimulators

Answer 15

8. Discuss the potential dangers associated with the following implants (deflection, induction of electrical currents, implant malfunction, etc.):
   h. Internal neurostimulators
   i. Not safe (Induction of electrical current)

Question 16

9. Define “exclusion zone”

Answer 16

9. Define “exclusion zone”
   a. Area in which the static magnetic field will interfere with electrically, magnetically, or mechanically activated devices
   b. Area within 5 Gauss line (0.0005 T), the area around an MRI magnet wherein the magnetic field is strong enough to interfere with medical devices (electrically, magnetically, or mechanically activated devices)

Question 17

10. Identify the type of MRI primary magnet that has the strongest main magnetic field and fringe field

Answer 17

10. Identify the type of MRI primary magnet that has the strongest main magnetic field and fringe field
    a. Superconducting electromagnet

Question 18

11. Identify the only type of MRI primary magnet that can be switched off when not in use

Answer 18

11. Identify the only type of MRI primary magnet that can be switched off when not in use
    a. Resistive electromagnet

Question 19

12. Identify the primary safety hazard associated with the secondary magnetic fields

Answer 19

12. Identify the primary safety hazard associated with the secondary magnetic fields
    a. Induction of current into a conductor

Question 20

13. Explain the first action to be taken in the event of a medical emergency in the magnet room

Answer 20

13. Explain the first action to be taken in the event of a medical emergency in the magnet room
    a. Remove the patient from the magnet room

Question 21

14. Explain the only instance in which a technologist should quench a superconducting electromagnet

Answer 21

14. Explain the only instance in which a technologist should quench a superconducting electromagnet
    a. Immediate danger of personal injury

Question 22

15. Explain where a person should position themselves if trapped in a magnet room during a magnet superconducting magnet quench if the gases vent into the room

Answer 22

15. Explain where a person should position themselves if trapped in a magnet room during a magnet superconducting magnet quench if the gases vent into the room
    a. Near the floor

Question 23

16. Explain the action to be taken if a patient is trapped in a magnet room into which cryogenic gases are venting

Answer 23

16. Explain the action to be taken if a patient is trapped in a magnet room into which cryogenic gases are venting
    a. Gain access to the room as quickly as possible

Question 24

17. Identify the only people who should handle cryogenic liquids

Answer 24

17. Identify the only people who should handle cryogenic liquids
    a. Trained service personnel

Question 25

18. Identify a hazard associated with cryogenic liquids

Answer 25

18. Identify a hazard associated with cryogenic liquids

a. Frostbite

Question 26

19. Explain the first actions to be taken in the event of a small fire in the magnet room

Answer 26

19. Explain the first actions to be taken in the event of a small fire in the magnet room
    a. Evacuate patient, turn off electricity to magnet, stay as near as possible to assure magnet safety of fire-fighting personnel

Question 27

20. Explain the first actions to be taken in the event of a large fire in the magnet room

Answer 27

20. Explain the first actions to be taken in the event of a large fire in the magnet room
    a. Evacuate patient, and quench the magnet