How Safe is that Imaging Test Flashcards
what is a sievert? SV unit?
Equivalent dose of radiation = absorbed + intensity
which is worse?
Alpha or beta
alpha particles
What are the particles what cause more damage?
Neutrons
Protons
alpha
What are the particles what cause less damage?
beta
gamma
what is effective dose?
amount and type of radiation + radiosensitivities of tisses/organs
effective and equivalent dose measured in?
SV sievert or mSV millisievert
example of a deterministic effect?
skin damage from sun exposure above threshold
what is probabilistic or stochastic effect?
no threshold for effect, eg. cancer
7 hour flight equivalent to?
CXR 0.04 or 0.05 mSV
what is natural background radiation exposure?
2mSV per year
each CT scan of abdomen is equivalent to?
1 year of smoking cancer risk (population basis)
one brain CT equivalent to how many background years?
1
one abdo and pelvis CT equivalent to how many background years?
12-15 yr
one L-spine CT equivalent to how many background years?
2
one chest CT equivalent to how many background years?
3-5 years
one abdo CT equivalent to how many background years?
8-10 or 4-10
what has replaced fluoroscopy?
endoscopy
2 kinds of oral contrast for CT?
Barium
gastrografin (iodine)
3 risks of intravascular contrast?
allergy
nephropathy
nephrogenic systemic fibrosis (MRI gadolinium)
why less allergies with CT contrasts these days?
now use non-ionic agents
contrast wil cause renal problems with people with eGFRs lower than? what to do?
40
prehydrate
another modality
scan without contrast
what happens if someone’s eGFR is below 40 and you give them gadolinium?
nephrogenic systemic fibrosis
hardened fibrous skin nodules and plaques
Contrast and Metformin?
stop metformin: risk of lactic acidosis
contract may cause thyrotoxicosis in someone with?
Graves or hyperthyroidism
what is you need a scan but they are getting treated for thyroid cancer?
don’t use the iodine contrast, will prevent the radioiodine from treatment
who can’t have MRI?
Aneurysm clips pacemaker neuro stims, implanted electrodes cochlear implants grindings/shrapnel