Daily Bolus of LR: Radiation doses in early pregnancy

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March 17, 2011 by dailybolusoflr

Radiation dose in early pregnancy

 

mSV or MilliSieverts is a measurement of the effective dose of ionizing radiation to the patient.  It is an average dose and does not reflect age or gender and does not reflect the higher radios-sensitivity of particular tissues.

 

  Before 2 weeks: > 100 mSv risk for spontaneous abortion (this is a VERY large dose…remember that a pan scan CT for trauma patients gives about 40 mSV)

  Teratogenic effects

  Between 2 and 16-20 weeks at doses of > 50-150 mSv there is evidence of teratogenesis. 

  50mSv is a high dose but in your trauma patient, you can come close. .re-scan the abdomen and pelvis once and you are over 50 mSV

  20 weeks: very unlikely to sustain any teratogenic effects even at higher doses

  Carcinogenic effects

  Always a risk

  Baseline risk of fatal childhood cancer 1 in 2000 (about 50% of childhood cancers are fatal)

  Fetal dose of 50 mSv is associated with a relative risk of 2 …this means that the risk of a fatal childhood cancer would increase to 1 in 1000 (the highest fetal dose from a single imaging study is from abdominal pelvic CT which equals about 15mSv)

 

For the purposes of the CDC table. .      0.05 Gy is equivalent to 50 mSv

Super complicated stuff. .but good to know there are some resources out there to help you talk to your patients.

 

http://www.bt.cdc.gov/radiation/prenatalphysician.asp

 

 

Linda Regan, MD FACEP

Program Director, Emergency Medicine Residency

Johns Hopkins Medical Institutions

1830 East Monument Street

Suite 6-100

Baltimore, MD 21287

Office: 410-955-5107

Office: 410-614-9823

Fax: 410-502-5146

lregan@jhmi.edu

 

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