Medically reviewed by Michelle Goñi, MD, Susan Kerrigan, MD and Marianne Madsen
Medical imaging has led to improvements in the diagnosis and treatment of numerous medical conditions in children and adults. As in many aspects of medicine, there are risks associated with the use of X-ray imaging, which uses ionizing radiation to generate images of the body.
The thinking person in the modern world wants to know if radiation from mammograms, bone density tests, computed tomography (CT) scans, and other imaging methods will increase their risk of developing cancer. For most people, there is very little risk from routine x-ray imaging such as mammography or dental x-rays. But many experts are concerned about an explosion in the use of higher radiation-dose tests, such as CT and nuclear imaging.
Balancing Benefits and Risk
What does “safe” mean? Does it mean there is no risk, or that the risk is very small? Do the benefits exceed the risk? Many activities carry some kind of risk. To call something safe usually means that it carries a low risk, not zero risk. Zero risk is almost impossible.
According to the FDA, the risk of developing cancer from medical imaging radiation exposure is generally very small, and it depends on factors such as:
- Radiation dose–the larger the dose and the more x-ray exposure that a patient has, the greater their lifetime cancer risk
- Patient’s age–the lifetime risk of cancer is larger for a patient who receives X-rays at a younger age than for one who receives them at an older age
- Body region–some organs are more radiosensitive than others
- Sex–women are at a somewhat higher lifetime risk than men for developing problems from radiation
Children are more at risk and performing x-rays on a pregnant woman can pose a risk for her developing baby. However, a radiodiagnostic procedure should not be withheld from a pregnant woman if the procedure is clearly indicated and if it can affect her medical care.
Early diagnosis and treatment far outweigh any radiation risk and by this definition, the examination is safe. When used in large quantities or when many examinations are performed, the risk from exposure to x-rays increases.
If you need a CT or nuclear scan to treat or diagnose a medical condition, the benefits usually outweigh the risks. However, it is reasonable to discuss with one’s physician whether the x-ray will prevent another more invasive procedure and weigh the benefits and risks. Furthermore, one is entitled to discuss the option of choosing a lower-dose radiation test. If your clinician recommends a CT or nuclear medicine scan, ask if another technique would work, such as a lower-dose x-ray or a test that uses no radiation, such as ultrasound (which uses high-frequency sound waves) or MRI (which relies on magnetic energy). Neither ultrasound or MRI appears to harm DNA or increase cancer risk.
The Whole Picture
Until there is more research and information on the effects of radiation, it is recommended that you keep your exposure to medical radiation as low as possible. This can be done in several ways, including:
- Reducing time spent near a radiation source. Minimize your time near a radiation source to only as long as it takes to accomplish a task.
- Maximize your distance from a radioactive source as much as possible. If you increase your distance from a radiation source, you will decrease your dose of radiation.
- Shield yourself from a radiation source–put something between you and the source. Physical radiation shielding can be accomplished with different forms of personal protective equipment (PPE).
- Consider less-frequent testing. If a person is getting regular CT scans for a chronic condition, they can ask their clinician if it’s possible to increase the time between scans. It is also an option to discuss whether a different approach can be taken, such as lower-dose imaging or observation without imaging.
- Don’t seek out scans. A patient need not ask for a CT scan just to feel assured that they have had a “thorough checkup.” CT scans rarely produce important findings in people without relevant symptoms. There is also a chance that the scan will find something incidental, spurring additional CT scans or x-rays that add to their radiation exposure.
The guiding principle of radiation safety is “ALARA”. ALARA stands for “as low as reasonably achievable.” This principle means that even if it is a small dose, if receiving that dose has no direct benefit, you should try to avoid it. To do this, you can use three basic protective measures in radiation safety: time, distance, and shielding.
Written by Joanne Myers
References
- FDA: Medical X-ray Imaging
- Investigation of radiation protection and safety measures in Rwandan public hospitals: Readiness for the implementation of the new regulations
- CDC: Radiation Safety
- Radiology Info
- Radiation and breast cancer: a review of current evidence
- “Doctor, will that x-ray harm my unborn child?”
- Radiation risk from medical imaging