X-Rays: Are They Safe?

Medical imaging tests help doctors diagnose diseases, from kidney stones and appendicitis to blockages in the coronary arteries and cancer.

But a recent wave of national news headlines say Americans may be having too many medical imaging procedures, exposing them to potentially harmful radiation.

So should you be concerned about screening or diagnostic tests?

“We always try to weigh the risks versus the benefits,” explains Talissa Altes, MD, a pediatric radiologist with UVA Children’s Hospital. “For patients who are having symptoms that something’s wrong, these tests are a way to diagnose and understand the problem. If your child has appendicitis, for example, the risk of injury from not detecting the appendicitis is much greater than the risk of having a CT scan. So these studies can be lifesaving.”

Daily Radiation Exposure

The culprit in certain medical imaging tests is “ionizing radiation,” a high-energy form of radiation that has the potential to damage DNA. Many medical imaging tests use radiation to create pictures of the inside of the body, including:

• X-rays
• Computed tomography (CT)
• Positron emission tomography (PET) scans
• Nuclear medicine studies

In very large doses, this type of radiation can increase a person’s risk of tissue damage, genetic malformations or cancer that may develop decades after exposure.

What most people don’t realize, however, is that they are exposed to low levels of this high frequency radiation every day. According to the American Cancer Society, the average person is exposed each year to about three mSv (millisieverts) of “background radiation” — radiation emitted from natural sources like radon (a natural gas) and cosmic rays from outer space and the sun.

“The amount of radiation from a chest X-ray, for example, is equivalent to a day or two’s worth of background radiation — it’s a tiny amount,” Altes says. “You get much more exposure by just living.”

Limiting Your Radiation Exposure

Even though the potential harm from medical testing is low, UVA radiologists are taking steps to minimize radiation exposure. UVA’s quality assurance program ensures that:

• Only the most up-to-date equipment is used
• The equipment is tested regularly by radiation physicists.

This modern equipment allows UVA’s radiologists to customize the amount of radiation for each patient by measuring their size, rather than using a one-size-fits-all approach.

Who’s Most at Risk from Radiation Exposure?

Children: Because children are still growing and developing, their body’s cells are undergoing rapid division, explains Altes. “These cells are most vulnerable to DNA damage and to becoming cancerous.” These effects aren’t likely to occur for 15 to 20 years after the X-ray exposure.

Obese patients: Larger patients need stronger doses of radiation to get a quality image, explains UVA electrophysiologist John Ferguson, MD. “For every six centimeters of soft tissue, you end up doubling the X-ray exposure,” he says.

Pregnant women: Radiation from medical imaging poses a slight risk of birth defects to the unborn child, particularly in early gestation. If an X-ray is absolutely necessary during pregnancy, UVA radiologists take special measures to protect the uterus and surrounding areas with a lead apron.

Weighing the Risks and Benefits

While the radiation from a single exposure to an X-ray is extremely low, there is concern about a person’s accumulated exposure to radiation over a lifetime.

For that reason, you should talk about your concerns about medical imaging tests with your doctors. Ask if there are non-radiation alternatives, such as ultrasounds or MRI (magnetic resonance imaging), that could yield the same results.

For most patients, the benefits of medical imaging far outweigh the risks of radiation exposure.