Time-Varying Gradient Basic: Auditory Considerations

Question 1

What specifically causes the sounds heard in MRI?

Answer 1

A torquing and vibration of the gradient coils against the bore as the two magnetic fields are competing.

Question 2

What is Lorentz force?

Answer 2

A torquing and vibration of the gradient coils against the bore

Question 3

What is the limit to how many decibels (dBA) the patient can be exposed to during an MRI?

Answer 3

99 dBA

Question 4

How many dB do earplugs need to reduce sound by?

Answer 4

10-30 dB

Question 5

What does the acronym NRR stand for?

Answer 5

Noise Reduction Rating

Question 6

Will increasing slice thickness increase or decrease acoustic noise?

Answer 6

decrease

Question 7

Will Low SAR mode increase or decrease acoustic noise?

Answer 7

decrease

Question 8

Will increasing TE increase or decrease acoustic noise?

Answer 8

decrease

Question 9

Will increasing FOV increase or decrease acoustic noise?

Answer 9

decrease

Question 10

Will decreasing image matric increase or decrease acoustic noise?

Answer 10

decrease because it decreases the phase gradient amplitude

Question 11

What is louder: DWI or SE?

Answer 11

DWI is louder than

Question 12

Will decreasing receiver bandwidth increase or decrease acoustic noise?

Answer 12

decrease noise by increasing echo spacing

Question 13

Do the OSHA occupational noise limits change based on the amount of exposure time?

Answer 13

Yes, limits change based on time. They range from 90 dB for 8 hours up to 115 dB for 0.25 hours.

Question 14

What is the dB sound limit?

Answer 14

140

Question 15

Are decibels measured in a direct scale or a logarithmic scale?

Answer 15

Logrythmic