unit 1 Flashcards
what does MRI stand for
magnetic resonance imaging
T/F: MRI is a non-ionizing radiation modality
true , no known long term effects
how does MRI create an image ?
images are based off of the body’s natural hydrogen atoms
if a patient has a lump or specific area of pain how do we mark it?
vitamin E capsule , shows up bright in MRI imaging
what type of patient will require screening done by spouses, family members, medical chart , and or additional exams
patients that are poor historians
if a patient has suspected intra occular metallic foreign bodies , how do you clear the patient
orbit x ray, cleared by radiologist
can a pregnant patient have contrast ?
no, as it can cross the placental barrier
if an MRI technologist is pregnant, what should they avoid?
entering the scan room during an active scan
if a site has a compatible oxygen tank that can be taken into the room what are they usually made of ?
aluminum material
most common hearing protection in MRI
ear plugs (foam)
what causes the noise from the MRI machine
switching of gradient magnetic fields
hearing protection is required, foam ear plugs reduce the noise about ____
15 decibels is all
T:F/ temporary hearing loss may occur after the exam
true
what should you do to prevent antenna effect , loop burns
make sure coil cables are not in direct contact with the patients bare skin
if a patient cannot be contacted verbally and visually they require more monitoring , or if they cannot communicate well. what would you use ?
pulse oximetry
ECG
blood pressure
what causes the hearing in MRI?
RF (radio frequency) pulses
SAR
specific absorption rate
SAR is expressed in
W/kg, watts per kilogram
whole body SAR
<4.0 W/kg
what patients tend to have a higher SAR
larger patients
how to reduce SAR
using fewer slices & using a 1.5 T vs a 3.0 T
average total exam time without contrast, repeats, or special sequences etc
30-45 minutes
the main effect of the RF exposure is
tissue heating
sensation of flashes of light, originates from stimulation by the induced electrical field
magnetophosphenes
signal misrepresentation or interruption
artifact
which plane divides the part into superior and inferior portions
axial
what plane divides the part into anterior and posterior portions
coronal plane
most common chemical used in MRI to cool the magnet and provide the magnetic the ability to create a magnetic field
liquid helium
repelled by the magnet, water and most biological tissue falls in this category
diamagnetic
usually means better image quality, but longer scan time
higher NEX/NSA
the staff technologist is usually only exposed to the _____ field while working
static
there is a theoretical risk to the fetal ____ for a pregnant patient or worker , but not proven
hearing
what MR personnel supervises the day to day safety of the unit
MRSO
rotational force that results from the magnetic force on an implanted device, such as a stent or clip
torque
during a quench cryogens are released which can lead to
hypothermia
cold burns
asphyxiation
the waiting room or area where the patient may be screened , change into their gown , and remove ferromagnetic objects and other devices it typically in zone
2
