BAKERSFIELD, Calif. -- While medical tests such as CAT scans, mammograms, and certain heart tests allow doctors to better diagnose potentially fatal conditions, these tests also expose patients to low doses of harmful radiation.

Because exposure to radiation has been linked to the development of cancer and leukemia, repeated radiation exposure through these medical tests has become a potential concern.

After following almost 100,000 adults for three years, a recent study by the National Council on Radiation Protection found that two-thirds of them had undergone medical tests that used radiation. On average, these tests had exposed them to twice as much radiation as would be expected had they not undergone the tests.

Because these tests are powerful diagnostic tools, researchers said in most cases the information they supply is worth the potential risk of radiation exposure.

However, researchers recommended that these risks be taken into account when deciding whether or not one of these tests is needed for diagnosis.