Radiation risk from medical imaging

Background

• Around 1.5-2.0% of the cancers diagnosed annually in the United States could be related to medial imaging
• Specific subsets of patients may be at greater risk from radiation exposure, and radiation risk should be considered carefully in these patients.
• The typical lag period between radiation exposure and cancer diagnosis is 1-2 decades or longer, thus radiation exposure reduction is less important in the elderly

Tests and Radiation Amounts

• 1 millisievert (mSv) = 0.1 rad (rd) = 1 millirem (mrem)
• 1 mSv is the dose received when exposed to 1 milligray (mG)

Procedure	Radiation Dose (mSv)	Additional Cancer Risk
		Male	Female
Comparison Doses
Yearly natural background exposure	3
7-hour Airline Flight	0.02
Plain Radiograph
Chest x-ray (2-views)	0.1	1 in 197,628	1 in 147,929
Pelvis x-ray	0.6	1 in 32,960	1 in 24,655
Neck x-ray	0.2	1 in 98,912	1 in 73,964
L-spine x-ray	1.5	1 in 13,184	1 in 9,863
Extremity x-ray	0.001	1 in 20,000,000	1 in 14,285,714
Computed Tomography
CT head	2	1 in 9,887	1 in 7,397
CT neck	6	1 in 3,296	1 in 2,466
CT L-spine	5.6	1 in 3,531	1 in 2,642
CT Pulmonary Angiography	15	1 in 1,318	1 in 986
CT Abdomen, Pelvis	14	1 in 1,413	1 in 1,057
CT Chest, Abdomen, Pelvis	21	1 in 942	1 in 704

Pregnancy

• Greatest risk of harm during organogenesis (3-8 WGA)
• IV contrast not teratogenic (class B)
• PO contrast not absorbed = no risk

Exposure Risk

• <5,000 mrads = safe
• ~10,000 mrads = small risk childhood cancer
• ~15,000^ mrads = 6% chance intellectual disability
• <3% chance childhood cancer

^Considered max

Always use shield when possible

See Also

• Radiation exposure (disaster)
• Acute Radiation Syndrome

External Links

• https://www.xrayrisk.com/index.php
• https://www.acr.org/-/media/ACR/Files/Radiology-Safety/Radiation-Safety/Dose-Reference-Card.pdf

External Links

• http://www.xrayrisk.com/