Table: 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 X-Rays of the Chest Anyone thought to have a heart disorder has chest x-rays taken from the front and the side. Typically, the person is standing upright, but chest x-rays can be done with people lying in bed if... read more (from back to front)	1	2.4 days
Mammography Mammography Breast cancer occurs when cells in the breast become abnormal and divide uncontrollably. Breast cancer usually starts in the glands that produce milk (lobules) or the tubes (ducts) that carry... read more	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 Cardiac Catheterization and Coronary Angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more 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.