Chapter 10 - MRI Safety

Question 1

What is SAR stand for and what is it?

Answer 1

Specific absorption rate

this is a way of measuring the USA food and drug administration limit for RF ( Rutherfordium chemcial) exposure.

Question 2

How many safety zones are there in MRI?

Answer 2

4

Question 3

If a patient is in the room with the magnet, this is considered what safety zone?

Answer 3

4

Question 4

What does safety zone #1 entail?

Answer 4

all areas that are freely available to the public ( AKA the hallway outside of MRI at the hospital)

Question 5

If a patient is answering their screening questions, they are likely in which safety zone?

Answer 5

2. This is where people are greeted and asked to do their screening.

Question 6

If an MRI tech is not with a patient and is just hanging out, she is likely in which safety zone?

Answer 6

3.

Question 7

If a patient is currently getting their scan done and are under the magnet, which safety zone is this?

Answer 7

4.

Question 8

Safety zone #4 should be marked as dangerous with a RED light and lighting sign.

True

Answer 8

True, this is the area in which the magnetic on and the patient is in the scanner.

Question 9

What is the difference between level 1 and level 2 MRI people?

Answer 9

Level 1- is like the front desk/office people ( like Ashely or Margaret) who are trained in the basic safety but not an actual MRI tech. They are even allowed in the safety zone #3 :O

Level 2- is a MRI tech or MD trained in safety.

Question 10

An item that poses no threat to MRI machines is considered a MR _______.

Safe, Conditional or, unsafe

Answer 10

MRI Safe

Question 11

A green square with the words MR in it means that an item is “MRI SAFE”

True or False

Answer 11

True

Question 12

What is an example of something that is considered MRI safe?

Answer 12

something plastic like a Petri Dish

Question 13

What does a yellow sign with the words MR stand for?

Answer 13

MRI Conditional

Question 14

What are the five major factors that are considered to have an impact on whether patients will have any side effects after having an MRI done?

Answer 14

1. Psychiological
2. The spatially varying static magnetic field
3. electromagnetic fields
4. Cryogens
5. Time-varying gradient magnetic fields.

Question 15

Some studies have shown that patients who have a brain scan sometimes have anxiety due to the close proximity and will require sedation of some sort.

true/ false

Answer 15

True

Question 16

The narrow bore of an MRI machine rarely causes patient’s anxiety.

True/ False

Answer 16

False. The narrow bore of a MRI machine plays a significant role in patient claustrophobia and anxiety when having a test done.

Question 17

At what stage of the exam are most patients the most scared/anxious?

Answer 17

the beginning.

Question 18

What are several ways we can help put the patient at ease during exam?

Answer 18

1. Aromatherapy
2. Wider machines
3. In-Scanner video presentations that include remainder of time of scan
4. Painting the ceiling tiles.
5. Sedation :)

Question 19

What are the 4 main implications for patient safety in regards to the static field?

Answer 19

1) transient biological effects
2) projectile hazards
3) Torque on implanted devices
4) Foreign bodies in static field.

Question 20

What is the main magnetic field called?

Answer 20

B

o

Question 21

The magnetic field is 160, 000 times more powerful than that of the earth.

True

Answer 21

True

Question 22

What are two temporary symptoms that are related to stepping into a magnetic field of 3-7?

Answer 22

Metallic taste in mouth and vertigo.

Question 23

What are symptoms that patients experience in fields of 7T and above?

Answer 23

Nausea, dizziness, vertigo, postural instability,

Question 24

What is thought to be the reasoning of why patients sometimes feel they are moving in a curved motion?

Answer 24

Caused by an overcompensation of the vestibular system ( in charge of balance) of the inner ear.

Question 25

This phenomenon causes the induction of an electrical current through a conductor that is moved through an external magnetic field. What is this called?

Answer 25

Faraday’s lay of electromagnetic induction.

Question 26

The magnet in the machine is not always on. The techs turn them off at the end of their shifts.

True or False

Answer 26

FALSE FALSE!!

The magnet is ALWAYS ON.

Question 27

What are some examples of an implanted medical device?

Answer 27

stents, clips, neurostimulators, pacemakers, hip replacements

Question 28

What is the word TORQUE mean in regards to MRI?

Answer 28

it is a term to describe a rotational force that causes the alignment of an object to the lines of magnetic flux.

This happens often with ferromagnetic implants such as pacemakers.

Question 29

if a patient has a hip replacement, is this likely to experience torque during the MRI?

Answer 29

no because they are anchored to the bone with screws and/or cement.

Question 30

A law that states that the direction of an induced current is always such as to oppose the change in the circuit or magnetic field that produces it.

Answer 30

Lenz Law

Question 31

What does the word “Ferromagnetic” mean?

Answer 31

something that has a high susceptibility to magnetization.

Question 32

True or False.

MRI does not use radiation.

Answer 32

TECHNICALLY false!!

MRI uses “non-ionizing” radiation.

Question 33

What does the word “quench/quenching” mean in MRI?

Answer 33

the sudden loss of the superconductivity of the magnetic coils so that the magnet becomes resistive.

Question 34

If someone has “stochastic effects from a MRI” , what does that mean?

Answer 34

effects that increase the probability of the patient developing a radiation- induced cancer at some time in the future

Question 35

What is a “deterministic effect”?

Answer 35

effects that can be shown to have a nonrandom cause and affect with the increased absorbed dose.

EX- erythema or hair loss.

Question 36

Much of the energy deployed by the rutherfordium pulse is absorbed by the patient’s body tissues which can cause an increase in thermodynamic temp.

True or false?

Answer 36

True

Question 37

Joules refers to the measurement of?

Answer 37

Energy

Question 38

Which areas of the body are more susceptible to heating than others?

Answer 38

Ees and the germ cells of the male reproductive system.

Question 39

What is the difference in 1st level controlled operating mode and 2nd level??

Answer 39

1st- mode of operation in which one or more outputs reach a value that may cause physiological stress which needs to be controlled.

2nd- mode of operation in which one more more outputs reach a value that can produced significant risks for subjects for which explicit ethical approval is required.

Question 40

What can happen to a patient during scan if they put their hands together?

Answer 40

it may produce a burn because this creates a biological circuit through which induced current may flow.

Question 41

GO back to antenna effect

Answer 41

jj