Merck Manual

Please confirm that you are not located inside the Russian Federation

Comparing Radiation Doses For Different Tests*

Comparing Radiation Doses For Different Tests*

Imaging Test

Number of Chest X-Rays Needed to Get the Same Dose

Approximate Environmental Exposure Equivalent to the Dose †

Single view chest x-ray (from back to front)

1

2.4 days

20

48 days

An x-ray series of the lumbar spine

75

180 days

CT of the head

100

243 days

CT of the abdomen

300–400

2–2.7 years

Coronary artery angiography during cardiac catheterization

350–750

2.3–4.9 years

* These doses account for how much radiation is delivered and how susceptible the body part exposed to radiation is to radiation damage.

† People are exposed constantly to low levels of naturally occurring radiation but the amount varies in different locations.

CT = computed tomography.