Is That Scan Really Necessary?

New report: Exposure to radiation from medical procedures has increased by a factor of seven in recent decades.

March 23, 2009

Quiz your doc: Ask if that imaging test is really needed.

RODALE NEWS, EMMAUS, PA—Advanced medical imaging tools such as computed tomography (a.k.a. CT, or sometimes CAT, scans) allow doctors to see what’s happening inside the body without actually opening it up. Which is undoubtedly a good thing, as it’s pretty much eliminated the concept of exploratory surgery. But a new report suggests that the resulting dramatic uptick in potentially unnecessary imaging procedures could be exposing us to unhealthy amounts of radiation.


THE DETAILS: The National Council on Radiation Protection and Measurements (NCRP) recently announced that Americans were exposed to more than seven times as much radiation from medical procedures in 2006 as they were in the early ’80s, largely due to a dramatic bump in CT and nuclear medicine (the branch of medicine and medical imaging that uses radioactive isotopes in the diagnosis of disease). Kenneth R. Kase, MD, senior vice president of the NCRP, reported: “These two imaging modalities alone contributed to 36 percent of the total radiation exposure [which includes background exposure from natural radiation in soil, rocks, and space], and 75 percent of the medical radiation exposure, of the U.S. population.” Since the dose of radiation used in most exams is very low, the medical benefit of the exam can outweigh the potential risk from the radiation. But radiation in any dosage can damage cells in the body, and so comes with some risk of triggering a health problem. With the surge in CTs, scientists are just now attempting to get a better sense of how much risk all these scans represent.

WHAT IT MEANS: The American College of Radiology (ACR) sees two trends at work here:

1: The vast improvement in imaging quality. Take the CT, which was developed in the early 1970s. For the first 25 years of scanning, the test could only make one image at a time. Today, radiologists can make up to 320 images simultaneously. When the resolution and the ability to image vascular structures vastly improved around 2000, the number of CTs skyrocketed.

2: The rise in “self-referrals,” or nonradiologists buying imaging equipment and prescribing in-office scans for their own patients. Radiologists typically get patient referrals from other physicians—they don’t order the scans themselves—so they can’t inflate the number of scans they perform. Nonradiologists who refer their patients to their own scanners for testing (and profit), can—and do, studies have proved. “We know from studies that when there’s financially motivated self-referral, the amount of imaging is, on average, twice as high as when there’s no financial incentive,” says James H. Thrall, MD, chair of the American College of Radiology.

Here’s how to make smart decisions about medical imaging tests:

• Get the whole picture. “Imaging has become the guiding hand of medical practice now,” says Dr. Thrall, “but that doesn’t mean it’s always necessary.” Before undergoing any scan, you should ask your physician why he or she ordered it. “There’s some level of risk to anything that’s done in the medical process, so you have to understand why you’re being advised to undertake a course of treatment,” continues Dr. Thrall. “Patients must challenge doctors and others to explain their rationale.” Here’s a list of questions to get you started:

‣ Why do I need this exam?
‣ How will having this exam improve my health care?
‣ Are there alternatives that do not use radiation that are equally good?
‣ Is this facility ACR-accredited?
‣ Does the physician ordering the scan have a financial interest in the facility’s providing the exam (i.e. do they directly profit from ordering the scan)?

• Control the amount of radiation your child receives. “Any organ that’s still developing is more sensitive to radiation than organs that have completed their growth cycle,” says Dr. Thrall. “So children and younger adults and, of course, fetuses are more susceptible to effects of radiation.” When imaging is prescribed for your child, be sure to ask your child’s doctor all five questions, above, and a sixth: Is my child receiving a “kid-size” dose of radiation? For more info on pediatric imaging, check out, an initiative of the Alliance for Radiation Safety in Pediatric Imaging.

• Make sure your scanner and the facilities are ACR-accredited. ACR accreditation ensures that the doc interpreting scans has met stringent education and training standards, the technologists operating the equipment are certified by the appropriate body, and the imaging equipment itself is examined regularly by a medical physicist to ensure that it’s functioning properly and taking optimal images. To find an ACR-accredited facility in your area, use the facility search page at

• Do your homework. For estimates of the radiation exposure from common imaging procedures, see the safety page on, a patient information site co-managed by the ACR and the Radiological Society of North America.