Rite ad 1 Flashcards
a 180 deg pulse contains how much more energy than a 90 deg pulse
4x
an aneurysm cip placed after 2019 at a reputible facility will place what risk to the patient
low
which half wavelength at 7t will place a patient at rish from burns
5-7 cm
according to the IEC 60601-233 doc, it is fine to scan a pregnant woman in the first trimester
false
according to the VA Health directive of 2013 it is recommended that how many techs be working within zone 2
two
A/m defines
magnetic field strength
as we increase body size, SAR will increase by how much
squared
as we increase field strength SAR will increase by how much
squared
BO defines
magnetic flux density
B1+rms is measured in what
W/kg J/kg microtesla
can a patient be scanned at 3t if the conditions state the device can be scanned at 128MHz
Yes
A condition states that an device can be scanned at 64MHZ, this means what
it can be scanned at 1.5TY
Copper has a weakly repulsive force in the presence of a magnetic source, it is considered what?
Diamagnetic
The created chance for induced current in a patient would be found at?
peripheral to isocenter
delivering more RF pulses to a patient will do what
increase heating
FPO:B will do what
it will limit B1+rms and slew rate
gadolinium contrast will to what to T1 and T2 relaxation
shorten it
how tightly packed the lines of magnetic flux are descibed how
magnetic flux density
an implant condition states an implant can be scanned only in normal mode. What does this mean
we are limited to 2W.kg whole body SAR
in a gradiant profile which of the following describes a period of time where the gradients are not changing
duty cycle
in a gradiant profile which of the following describes the strength a gradient will be activated in mT/m
maximun gradient
increasing TR will __________induced currents in our p[atient
decrease
iron has a very strong attractive force in the presence of a magnet this is considered
ferromagnetic
it is acceptable to use an MRI screening sheet which was completed 3 days prior to the patient receiving an MRI
false
magnetic flux travel from the _____pole to the ______pole of a mangetic source
North South
magnetophosphenes and confusion can occur after a quench and is caused by what
deteriorating magnetic field
normal mode limits the operation of the gradient coils to_________its maximum
80%
an object is strongly attracted to a magnetic source we can say that an object that behaves this way has a ______susceptibility
high
patients shoulder remove their street clothes and any jewelry prior to having an MRI to reduce risk of injury
true
the purpose of an MRi screening sheet is to do what
evaluate for any risks to the patient
reducing which of the following will promote less heating in our patinet
echo train length
the RF field will determine which of the following primarily
heating
SAR in the controlled operating mode are measured over what period of time
6 min
SAR is measured in
W/kg
SAR limites are set for which of the following
individual pulse sequences
SED is measure in what
J/kg
Steeper gradient which are switching fast will ________induced currents
increase
titanium has a weakly attractive force in the presence of a magnetc field. It is considered
paramagnetic
what are risk factors that require labs to be drawn on a patient
an kidney issues/singel kidny/diabetes
what cryogen do we use in MRI
helium
what does B1 refer to
time varying RF field
what does the + refer to in B1+rms
the energy yielding portion of the RF field
what does the rms refer to in B1+rms
rounded value of energy producing RF
what is a reason we may need to release helium from an MRI unit
uncontrollable fire in zone 4
what is it called when we release the helium out of the MRI unit
quench
what is the black box limit for eGFR where patients are recommended no to have contrast
30
what is the associated level of risk associated with a copper T IUD
low
what is the level of risk associated with a cardiac stent
low
what is the limit of the SAR to the head in first level operating mode
3
.2W/kg
what is the limit of the static magnetic field in the first operating mode
8T
