Think back to the last time you had an X-ray: The radiologic technologist probably placed a lead apron over part of your body to protect it from radiation. That’s now an outdated practice: The American Association of Physicists in Medicine no longer supports shielding patients’ reproductive organs and fetuses during imaging studies that use radiation, such as X-rays and CT scans.
Changing this practice has been a near impossible feat.
While the association’s statement rocks the boat of convention, it’s based on mounting evidence that shielding is not as helpful as once thought, and it might even have negative consequences.
One of the downsides is that shielding can obscure the imaging field, leading to an unusable X-ray or CT scan, requiring the patient to have another. That increases his or her radiation exposure. One study found that shields were misplaced half of the time during pelvic X-rays and often obscured important bony landmarks.
Another concern is that most imaging machines that use radiation automatically determine the dose of radiation required to produce a successful image. If the machine senses a shield, it increases the dose in an effort to image through the shield, leading to an increase in radiation exposure.
There are few positive effects to shielding. The chance of radiation exposure outside the beam’s scope is already minimal. If reproductive organs or a fetus are outside the beam’s path, there is no reason to shield. A Mayo Clinic study found that shielding the abdomen or pelvis during chest CT scans didn’t actually reduce the dose of radiation enough to justify the risk of artifacts in the imaging field.
There are two important exceptions to changing the practice of shielding. First, it still applies to providers. “Health care professionals who regularly use radiation, such as radiologic technologists or surgeons, have a higher rate of exposure day in and day out than a single patient undergoing an imaging study,” says Jennifer O’Riorden, director of health physics and radiation safety officer at Lahey Medical Center in Burlington, Mass. “These providers should continue to wear the appropriate protective apparel.”
Second, shielding should be used if or when it offers patients a psychological benefit. Some patients may be nervous if their provider doesn’t automatically shield them during an X-ray or CT or nuclear imaging scan. Rebecca Marsh, a medical physicist and author of the journal article that served as the framework for the American Association of Physicists in Medicine statement, suggests that providers should talk with their patients about the risks of shielding but still make the professional decision to shield if the comfort it provides outweighs the risks.
Given the evidence and the current guidelines, why is it so hard to change the status quo?
First, radiation is a very real fear for many people, partly because of past disasters. Chernobyl, Hiroshima, and Fukushima are very public demonstrations of the power of radiation gone wrong. In the clinical setting, the fear of radiation is also likely due to a lack of education and understanding of exposure and risk.
A survey of patients in an emergency department found that most do not accurately understand the radiation dose associated with various imaging studies: Standard X-rays use a negligible amount of radiation; CT scans and nuclear imaging use the most. Only 14% of those surveyed said that CT scans use more radiation than chest X-rays. Less than one-quarter accurately said that MRIs do not use radiation at all. A separate survey found that even medical providers do not always fully understand radiation exposure and risk.
Another reason it is hard to move away from shielding is that it is a deeply engrained practice for both patients and providers. “Provider education has always been based on the ALARA principle — as low as reasonably achievable — using time, distance, and shielding to minimize the radiation dose,” says O’Riorden. Patients have come to expect it, too.
Shielding reproductive organs and fetuses became the norm in the mid-1900s because experts worried that radiation-induced genetic mutations in sperm or eggs could be passed on to a patient’s future children. It’s worth noting that hereditary mutations due to radiation exposure have never been clinically documented. The federal government issued regulations in the 1970s recommending shielding, solidifying the practice. (The Food and Drug Administration is considering revising these regulations later this year.)
These recommendations and conversations leave out an important stakeholder: dentists. About half of the X-rays completed in the U.S. each year are done in dentists’ offices, not doctors’ offices. Shielding is less likely to interfere with a dental X-ray, or even be necessary for it. It seems logical that dentists would be willing to adopt new guidelines about shielding, but they were left out of the push to change the status quo. That was a huge oversight. (In the United Kingdom, dentists have been asked to cease “the widespread practice of applying patient contact shielding.”) If U.S. dentists continue to shield their patients while doctors don’t, there is potential for considerable confusion among patients.
Radiation exposure is an example of the risk/benefit trade-off we make with every decision. When imaging studies that use radiation are clinically appropriate, the benefits far outweigh the risks and shielding does little to mitigate those risks. “When it comes to patient safety and radiation risk, it is very important — yet difficult — to not let emotions and fear overrule an unbiased evaluation of available data,” says Marsh.
Fear and tradition are powerful forces that often work against change. Aligning current guidelines with the growing evidence that suggests shielding is not protective will take buy-in from both providers and patients. But to earn that, we must focus first on conversations that address the engrained fear of medical radiation and misunderstanding about it.
Elsa Pearson is a senior policy analyst at Boston University School of Public Health.