Imaging Tests: Weighing the Radiation Risk
Ask if that CT scan – for you or your child – is really needed.
CT scans are a valuable tool for doctors to detect cancers, cardiovascular disease, infections and other conditions, which is why about 75 million of them are done each year in the U.S.
Questions to Raise
If a CT is indicated, Smith-Bindman says, be explicit that you’d like that test done at the lowest dose possible – with the doctor who’s ordering it, the technologist who’s doing it and the radiologist who’s interpreting it. When deciding whether to consent to a CT for you or child, here's what to ask:
If a CT is indicated, Smith-Bindman says, be explicit that you’d like that test done at the lowest dose possible – with the doctor who’s ordering it, the technologist who’s doing it and the radiologist who’s interpreting it. When deciding whether to consent to a CT for you or child, here's what to ask:
- Is the test medical necessary? If so, do I need it now or can it wait?
- Extent of the test: Are you doing the chest, abdominal and pelvis? Do you need all of those, or do you only need one?
- Will my child receive the right dose for his or her size?
- For cancer survivors, families may need to decide whether to do follow-up tests near home or stick with the children’s hospital, Ritzwoller says. If so, ask: Will low-dose CT be available at the local hospital? Are radiologists well-versed in pediatric doses?
- Is there an alternative test? Smith-Bindman, who just did a study comparing CT and ultrasound for spotting kidney stones, found the latter test was just as accurate.
- Is it possible to do a single-phase rather than a multiple-phase CT exam?
- To make an informed decision, Smith-Bindman says, ask the medical team: "Help me understand what the benefit is so I can balance it against the risk."
- Besides asking if the exam is necessary, parents should also ask why it’s necessary and whether the results will change the child’s care, Miglioretti says.
Parents can also lower risk by avoiding repeat exams, she adds. “Sometimes when a child sees multiple physicians, they might repeat the exam. But the parent should always bring the other exam with them, and make sure a second test is really necessary if they’ve already had a CT,” she says.
Proceed With Caution
For its part, the American College of Radiology points to studies from Germany and France that suggest the CT-cancer risk remains to be proved.
"According to recent French and German studies, it becomes clear that the direct cancer risk for solid tumors and lymphomas attributed to CT scans is not so accurate as some have claimed," says James Brink, vice chair of the ACR Board of Chancellors and radiologist-in-chief at Massachusetts General Hospital.
However, experts agree that while patients or parents should not hesitate to have a medically necessary CT scan, caution and standardization are needed.
"Recognizing the limits of epidemiological research does not mean medical radiation is not to be respected or scans done indiscriminately," Brink says. "Providers and patients should talk about benefits of medical imaging procedures. ACR just wants to ensure that up-to-date information is used in that discussion."
Safety Movement
Many groups are working to make CTs safer, standardize radiation doses among facilities and keep them as low as possible, use alternative methods when appropriate and avoid unnecessary scans.
As part of the Choosing Wisely initiative, organizations including the American College of Emergency Physicians, American Society of Clinical Oncology and American Academy of Pediatrics give guidance on when procedures such as CT scans should be avoided.
The Image Wisely initiative addresses radiation safety for adults. Image Gently, which focuses on children, provides information on imaging tests for physicians, radiologists, technologists and parents.
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