Exam (elaborations)
MRSO IMPLANTS AND DEVICES MODULE 5 QUESTIONS AND ANSWERS
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MRSO IMPLANTS AND DEVICES MODULE 5 QUESTIONS AND ANSWERS
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Name: Score:90 Multiple choice questions
Term 1 of 90
According to ASTM, MR Unsafe is applied to items that:
in writing (faxed reports are acceptable)
Item that poses unacceptable risk in MR environment
tested and labeled for use in your particular MR environment
patient's medical record
Term 2 of 90
When evaluating conditions of an implant regarding spatial gradient, the SYSTEM'S maximum
spatial field gradient is irrelevant. The spatial field gradient amount that should be considered
is
region where the dB/dx is stronger
field strength (due to heating from varying wave length)
The maximum at which the object will be EXPOSED
-torque and force
-vibration
-device interactions
Term 3 of 90
B1+rms expresses
Average of the RF power over time
an item's tendency to align along the direction (axis) of B0 as it is magnetized
at given field strength, items are as magnetically saturated as they will become
homogenous and at maximum
,Term 4 of 90
RF Frequency is determined by
displacement force exerted on an object in a spatial field gradient
-Torque/rotation (B0)
-Translation/displacement (B0)
-RF Frequency/Wavelength (B1)
-verbal and interactive
-performed by Level 2 MR Personnel
Larmor equation
Resonant frequency = static field x gyromagnetic ratio
Term 5 of 90
Heating and SAR:
homogenous and at maximum
are UNRELATED
Average of the RF power over time
simplified
Term 6 of 90
Maximum torque is at
micro-Tesla
isocenter
B0(dB/dx)
simplified
,Term 7 of 90
Slew rate decreases with
the torque force exerted on an item by B0 should be less than the force of gravity
-thicker slices
-larger fov
-reduced receiver bandwidth
-normal mode
-acoustic reduction vendor options
-current in conductive leads
-vibration
-new devices introduced
-most new devices are mr conditional
-labeling changes: design / models / test data / adverse events
Term 8 of 90
International standards for testing were developed by
6 weeks although not necessary unless specifically required by labeling
radiologist
ASTM task group
device manufacturer
Term 9 of 90
Conditions regarding safety and compatibility applies only to
patient's medical record
specifically tested conditions
Item that poses unacceptable risk in MR environment
off-label (device was not tested)
, Term 10 of 90
All testing is designed for
radiologist
increasing frequency of RF
cylindrical bore MR systems only
are NOT all the same
Term 11 of 90
Martensitic
device manufacturer
things designed to hold and edge. Highly ferromagnetic. (surgical stainless)
radiologist
the device manufacturer
Term 12 of 90
Deflection angle is measured by the ASTM using
protractor placed at entrance of the bore near the bore wall. If the deflection angle
measures less than 45 degrees, the magnetically induced force is less than the force of
gravity
patient's medical record
-thicker slices
-larger fov
-reduced receiver bandwidth
-normal mode
-acoustic reduction vendor options
deflection angle is determined then extrapolated to a theoretical "fail point"
-measured angle was likely very small, meaning there should be no concerns regarding
spatial gradients
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