General & Patient Safety Flashcards
Mechanism of contrast induced nephropathy?
ATN due to toxic effect on tubules
Most frequent cause of lawsuit- perceptual or interpretive error?
Perceptual error
When should prophylactic steroids be taken before a CT with contrast study?
13 hrs then 1 hr before scan
What effect does voxel size have in MRI?
Increased SNR but reduced spatial resolution
What effect does FOV have in MRI?
Increased FOV implies reduced matrix size
This means increased SNR but reduced spatial resolution
What limits speed in FSE MRI?
Specific absorption rate
How does STIR sequence work?
Produces fat suppression through relaxation phenomena
What is NSF?
Nephrogenic systemic fibrosis
Generalised fibrosing disorder occurring in patient with renal failure exposed to Gd
Free Gd usually (chelated sometimes)
Spares cubital and popliteal fossa
CXR radiation dose?
0.02 mSv
AXR: how many CXR equivalent?
50
CT brain, AP and PA?
CT brain: 100
CT AP: 300-500
CT PA: 400
VQ, PET and bone scan?
VQ: 50
Bone scan: 200
PET: 700
Beta decay?
Too many neutrons. 1 neutron gets converted into a proton and an electron which gets ejected
Positron decay?
Too many protons. A proton gets converted into a neutron and a positron which gets emitted.
Tc 99m: what type of gamma rays emitted and half life?
Produced from Mo-99
Emits 140 keV gamma rays
Half life 6 hours (94% decays to Tc-99 in 24 hrs)
