Exam Approximate effective dose Background radiation equivalent
Abdomen Pelvis CT 10 mSv 3 years
Spine Radiograph 1.5 mSv 6 months
Extremity Radiograph 0.001 mSv 3 hours
Head CT 2 mSv 8 months
Spine CT 6 mSv 2 years
Chest CT 7 mSv 2 years
Screening Low-Dose Chest CT 1.5 mSv 6 months
Chest X-ray 0.1 mSv 10 days
Coronary CTA 12 mSv 4 years
Cardiac Calcium Scoring 3 mSv 1 year
Mammography 0.4 mSv 7 weeks
DEXA 0.001 mSv 3 hours
Dental X-ray 0.005 mSv 1 day
PET/CT 25 mSv 8 years


Note: 1 mSv is the dose produced by exposure to 1 milligray (mGy) of radiation

CTDIvol: measure of the dose per slice of a CT scan. Useful to compare protocol to protocol or scanner to scanner. Less useful for determination of actual patient dose received. Measured in mGy

DLP: The dose actually delivered to the patient for a particular scan. Calculated as the CTDIvol x the length of the scanned volume (called the Z-axis length). Measured in mGy*cm.