Radiation safety in medical testing has been a hot media topic. More imaging tests that use radiation are available than in the past and, though the risks are typically minimal, they bear consideration. However, it is also important to note that these imaging tests allow physicians to see the internal structures of the body in ways that previously weren’t possible. Many of today’s life-saving and life-improving treatments could not be delivered without the advancements made in medical imaging.
How Is Radiation Used in Medical Testing?
Radiation is energy that travels in waves. The radiation used in medical imaging is a type with charged particles in the atom that is called ionizing radiation. This type of radiation can be beamed at or placed in your body, and it will pass through, be absorbed or be reflected by different types of tissues. The amount of radiation that passes through or bounces back from tissues in the body can be translated into images, and allow physicians to see bones, organs, blood vessels and other structures in the body to see if they are healthy or diseased. Think, for example, of an x-ray, which is the oldest form of medical imaging and has been in use in various forms for over 100 years.
Modern imaging tests that use radiation include x-ray, computed tomography (CT) scans, angiography, nuclear stress testing and radionuclide scanning. These imaging tests and others have revolutionized medicine and have largely made exploratory surgery (using surgery to identify disease) obsolete.
How Do Radiation Doses for Tests Compare?
Radiation occurs naturally all around us. We are constantly exposed to radiation from outer space, from elements in the soil and from other natural and artificial sources. The human body even emits radiation because of the presence of certain forms of potassium and carbon. All of this radiation is referred to as background radiation. Understanding how much radiation each of us is exposed to in a year just through daily living can help provide context for radiation amounts from medical tests.
Radiation dose is measured with a unit called a millisievert (mSv). While amounts of background radiation vary depending on where you live, the average dose per year in the United States is 3 mSv.
Why Are People Concerned About Radiation Doses?
Ionizing radiation exposure can cause a number of health problems. It can increase a person’s lifetime risk of cancer. Additionally, it can result in tissue damage if one area of the body receives a high dose. A third concern is that radiation exposure can harm a fetus if a pregnant woman is exposed. (If you are or may be pregnant, it is important to notify your physician/practitioner before any tests using radiation are performed.)
According to the U.S. Food and Drug Administration (FDA), a CT scan, for example, of some portion of the body resulting in a 10 mSv dose is believed to increase the risk of fatal cancer by 1 in 2000. The risk of fatal cancer in the United States overall is 1 in 5. So while the CT scan will raise cancer risk, it does so at a rate that is very small compared to the existing risk. Another way of thinking about it is that the CT scan dose is less than what the average American will be exposed to from background radiation over a period of 4 years.
However, while one test that uses radiation may not raise cancer risk substantially, cumulative lifetime radiation dose matters. Risk for cancer increases as a person is exposed to radiation over years and a lifetime, not just in single instances of exposure.
If you have already had a number of radiation-based imaging tests in the past (x-rays, CT scans, etc.), you should make sure your physician is aware of this. You may also want to keep a list of tests you have undergone as part of a personal medical history file that you can keep at home for reference.
What Safety Measures Are in Place to Reduce Radiation Risk?
The safety measures that are in place to reduce your radiation dose during a test vary according to the test. Typically, these safety measures include shielding to limit radiation exposure to the area of the body under study and monitoring of the dose that is being given to be sure it is within acceptable limits.
Additionally, the Society for Cardiovascular Angiography and Interventions (SCAI) has issued recommendations (“Radiation Safety Program for the Cardiac Catheterization Laboratory”) for best radiation practices for interventional cardiologists, the specially trained physicians who perform catheter-based procedures such as angioplasty and stenting in a hospital’s catheterization laboratory. These recommendations and other professional standards guide the ordering and use of diagnostic tests.
Click here for questions that can help you start a conversation with your doctor about tests that use radiation.