coils and field Flashcards
which of the followings primary biological effect is tissue heating/deposition
oscillating magnetic fields (radiofrequency)
the orientation of the main magnetic field in a high field superconduction short bore magnet is
horizontal
the measure of radiofrequency absorption is delineated as
watts per kilogram
the effects of time varying magnetic fields can include all of the following
peripeheral nerve stimulation, acoustic damage/hearing loss magnetophosphenes
current FDA limits on time varying magnetic fields are
once the patient experiences peripheral nerve stimulation
which of the following sequences would be more at risk for the effects that time varying magnetic fields can cause
EPI
the gradient rise time is defined as the
time it takes for the gradient to reach its full amplitude
the gradient slew rate is the
rate of speed of ascent or descent of a gradient from zero to its max amplitude
magnetic field inhomogeneity is expressed in
parts per million
utilization of surface coils yields al of the following
more localized smaller FOV capability with increased SNR , providing opportunity for thinner slices on most sytems
RF heating is more of a concern in
Fast spin echos
multiple coil elements combined with multiple receiver channels make a
phased array coil
a 6 in surface coil is able to receive signal
3 in deep into the patient
