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This week's monday pearl is from our very own Azher Merchant....who recently gave an excellent talk on the risks of radiation.
Be afraid....be very afraid....
Radiation Risk:
Risk is based on acute exposure and is extrapolated largely from atomic bomb survivors.
Effective radiation dose = Sievert (Sv)
Adults:
Lifetime Attributable Risk of Cancer 1:1000 at 10mSv
Lifetime Attributable Risk of Cancer Mortality 1:2000 at 10mSv
Risk estimates follow a linear rate of change such that:
Lifetime Attributable Risk of Cancer in Adults = Radiation Dose (mSv) x 0.0001
Risk is Cumulative
Pediatrics:
Lifetime Attributable Risk of Cancer is greater than for adults and is age-dependent
Lifetime Attributable Risk of Cancer Mortality 1:1000 at 10mSv
Common Effective Dose Estimates (mSv)
Background radiation 3.5/year (chronic exposure)
CXR 0.1
CT
Head, Face 2
Neck, Cervical Spine 2
Chest, Thoracic Spine 8
Abdomen 7.5
Pelvis 7.5
Abdomen/Pelvis, Lumbar Spine 15
Extremity 0.5
Note that it doesn't take very much radiation to reach the 10 mSv level!
Bottom line: CT if you need to, but carefully consider whether it is worth it or not
One last pearl, carefully consider whether or not you want that d-dimer and don't order one unless you are prepared to order a CT scan.