CAMRT Practice Exam
Is SNR proportional or inversely proportional to voxel volume - ANS-Proportional
3 fields used in MRI - ANS--static magnetic field
-TVMF (gradient field)
-RF field
3 main types of magnets used - ANS--Superconducting (most common_
-Resistive
-Permanent
FDA limits for the 3 fields in MRI - ANS-Static field: 2T
TVMF: 3T/s
RF field:
- does not cause an increase in temperature of more than .5 deg C or any body part of 1
deg C
-SAR does not exceed 1W/kg avg over 25% of whole body for longer than 15mins
-SAR does not exceed 2W/kg avg over 25% of whole body for durations of 15mins or
less
Eddy currents are caused by - ANS-TVMF (gradients)
What are Eddy Currents - ANS-Small currents induced in the body via the TVMF
Biological effects of the TVMF - ANS--Fibrillation
-Electroshock
-Visual phosphenes
-Peripheral nerve stimulation
SAR meaning and units - ANS-Specific Absorption Rate
W/kg- Watts/kilogram
Which field is responsible for tissue heating and temperature increase - ANS-The RF
field
How are cardiac pacemakers affected in MRI - ANS-Affected by all 3 fields
-Static field affects the operation and also exerts torque
,-TVMF and RF field can interfere with circuitry
3 types of ferromagnetic materials? - ANS-iron, cobalt, nickel
Level 2 MR Personnel - ANS-Those more extensively trained and educated in MRI
safety
How many times should a non emergent patient be screened - ANS-Twice, once
verbally with a level 2 MR Tech
How should emergent patients and their non MR personnel be screened - ANS-Once
How should unconscious/ unresponsive patients be screened - ANS-- A family member
should fill out the screening form
-If no reliable history can be obtained and MR exam cannot wait they must undergo
plain film radiography of head/neck, chest, abdomen/pelvis, upper arms and thighs
How should children and teens be screened - ANS-Twice, once in front of parents and
once without
MRI and pregnant patients - ANS-No known harmful effects but risk vs benefit
assessment should be made
MRI contrast and pregnant patients - ANS-Should not be routinely given to pregnant
patients but risk vs benefit assessment needed
What is the spatial field gradient - ANS-The variance in the fixed static field surrounding
the scanner, the manufacturerer supplies a SFG map
Lenz forces - ANS-Faradays law states that a changing magnetic field will induce a
current in a conductor, Lenzs law states that the induced current will generate a
secondary field that opposes the original field
Normal respiratory ranges - ANS-Adult: 15-20 breaths per minute
Infant: 30-60 breaths per minute
Normal pulse oximetry - ANS-95%-100%
Tachycardia - ANS-Fast heart rate over 100 bpm
Bradycardia - ANS-Slow heart rate less than 60 bpm
Spots to get a pulse reading - ANS--Radial (wrist)
-Carotid (neck)
-Popliteal (knee)
-Temporal (head)
-Brachial (elbow)
-Dorsalis pedis (foot)
-Femoral(leg)
Most accurate spot for pulse rate in infants - ANS-Apical over apex of the heart
Normal BP ranges - ANS-Adult: 80-120mmHg/60-80mmHg
Child: 90-120mmHg/50-70mmHg
Infant: 85-130mmHg/45-85mmHg
3 types of motion in an atom - ANS-(1) Electron on its axis (2) Electron around the
nucleus (3) Nucleus on its axis
Isotope of hydrogen - ANS-protium (MR active nuclei)
True or false: Hydrogen nuclei only align themselves to the field in 2 directions -
ANS-True
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Hkane. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
