MR HARDWARE AND SAFETY Flashcards
What is the external static field called?
B0
Which magnetic field CANNOT be turned off?
Permanet magnet
Which magnet can easily be turned off or removed?
Resistance magnet
Reducing temperature of the conductor reduces what?
Resistance
Which cryogen is most used for superconducting temperature?
Helium
What is a sudden loss of conductivity called?
Quench
What is the highest strength magnet?
Superconductive magnet
What is the magnetic direction of a cylindrical machine?
Z-axis
What is in the walls of the MR room to passively magnetic shield?
Iron
What is the adults FDA guideline for magnetic exposure?
8 Tesla
What is a biological effect from elevation of TWAVE during scan process called?
Magnetohydrodynamic effect
What is rotation or torque greatest at?
Isocenter
Which material is used for RF shielding?
Copper
Which coil uses two elements to produce two waveforms 90 degrees out of phase with each other?
Multi-channel phased array
FDA guideline limits for SAR for head:
3.2w/kg
FDA guideline limits for SAR for whole body:
4.0w/kg
FDA guideline limits for SAR should be no greater than:
2.0w/kg
Increasing flip angle from 45 to 90 degrees will increase SAR by a factor of:
4
Which sequence is most concerned with SAR?
Fast spin echo sequence
True or false: Patient can get burned
True
What is the primary purpose of a gradient magnetic field?
To spatial encode the MR signals
What is the head to foot direction?
Z
What is Slew rate defined as?
Maximum amplitude divided by rise time
FDA hearing protection is needed for sound levels of:
> 99dB
Which zone is the control room?
Zone 3
Metal device that can be safely brought into zone 4 should be:
MR conditional
Person that is responsible for final decision of PT:
Radiologist
How to screen for metal fragments in the eyes?
Radiographs
