Week 1 Flashcards
MRI scanner types
- permanent
- resistive electro
- superconducting
1 Tesla = ___ Gauss
10,000
Ultra-Low Field Tesla Strength
0.02 - 0.1 T
Low Field Tesla Strength
0.2 - 0.6 T
Mid Field Tesla Strength
1 - 1.5 T
High Field Tesla Strength
2 - 4 T
Ultra-High Field Tesla Strength
> 7 T
why do MRI need strong coolants
as temp decrease, metal resistance falls. when it drops to zero, electricity is conducted without energy loss as heat due to resistance
superconducting MR magnets typically use ___ wires
Nobium-Titanium, Tc = 9.4K
what is commonly used as a coolant / cryogen to lower temperature
liquid helium (4K)
HTS
high temperature superconductive
types of magnetic properties of materials
diamagnetic, paramagnetic, ferromagnetic
diamagnetic material properties
no intrinsic atomic magnetic moment but weakly repels magnetic field = small negative magnetic susceptibility
paramagnetic material properties
ions have unpaired electrons, resulting in a positive magnetic susceptibility less than ferromagnetic materials
MR Safe
item poses no hazard from exposure to MR environment
MR conditional
item with demonstrated safety in MR environment within defined conditions
MR unsafe
item poses unacceptable risks to patients within MR environment
how many preventive procedural zones
4
Zone I
freely accessible to general public
Zone II
screening & interviewing patients but patients may not be able to move freely throughout
Zone III
controlled area - access entirely under supervision of MR personnel
Zone IV
MR scanner room - highly restricted; non-MR personnel must be under immediate visual supervision of qualified MR personnel
MRI preventive procedures
- ferromagnetic detectors
- screening questionnaire
clinical MRI involves imaging of ___
hydrogen nuclei (protons)
