As radiation can be harmful, great care is taken to limit the intensity and length of exposure from chest x-rays and to avoid unnecessary radiography. The average time of exposure for a chest x-ray is very brief - averaging less than one-half of a second. In addition, technologists are trained to focus the radiation beam, minimizing exposure to other parts of the body. Lead shielding is used to protect the lower abdomen and x-rays are not prescribed for pregnant women unless absolutely necessary.

Advances in x-ray technology have dramatically reduced the amount of radiation necessary to produce good images. X-ray film is much faster than formerly and digital technology has also increased the rate of image-taking. Today's patient normally receives between 2-5% of the radiation exposure during a chest x-ray experienced by a patient of 30 years ago.

A single x-ray now only involves a radiation level of about 8 millirems. When compared to normal "environmental radiation" (averaging 325 millirems per year) from the sun, cosmic sources, rocks, soil, building materials, and even the food we eat, the radiation from a chest x-ray is proportionally quite small. (Radon gas is by far the main source of radiation in the environment.) Background radiation increases with elevation above sea level. A cross country trip by jet in the USA exposes a passenger to nearly as much additional radiation as a chest x-ray. Smoking cigarettes increases radiation exposure by 280 millirems per year - the equivalent of 35 chest x-rays. All forms of medical radiation - including high dosage radiation for the treatment of cancers - account for only about 15% of annual radiation exposure in the USA.

The patient with congenital heart disease is often exposed to more radiation during other aspects of treatment than during chest radiography. X-rays are also used during cardiac catheterization procedures, which are useful in determining heart physiology, hemodynamics, areas of obstruction, and other cardiac features. Radiography is also useful in the placement of devices for treatment, such as catheters, occlusion devices, and pacemakers. Nevertheless, radiation exposure from these procedures is relatively low and involves very little risk.