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....
Risk is based on acute exposure and is extrapolated largely from atomic bomb survivors.
Effective radiation dose = Sievert (Sv)
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
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)
Head, Face 2
Neck, Cervical Spine 2
Chest, Thoracic Spine 8
Abdomen/Pelvis, Lumbar Spine 15
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.