Overuse of CT Scans Raises Radiation Concerns

Up to half of imaging tests may be medically unnecessary

Diagnostic imaging has helped many patients avoid exploratory surgery, but it has also spawned concerns about misuse, according to a report from Kaiser Health News.

Experts cite ballooning costs, potential harm from the tests themselves, and the overtreatment of harmless conditions found during scans. These “incidentalomas” — so named because they are found unexpectedly — include benign lung and thyroid nodules and other common conditions that can lead to unnecessary and expensive workups as well as treatment that can cause complications.

Much of the attention has focused on computed tomography (CT) scans, which use hundreds of x-rays to create detailed three-dimensional images. Like x-rays and positron emission tomography (PET) scans, CT scans involve ionizing radiation, which can damage DNA and cause cancer.

Although CT scans have become an essential diagnostic tool, the FDA reports that an estimated 30% to 50% of imaging tests are believed to be medically unnecessary, the Kaiser report says.

“We have this view that we only use imaging when it’s really necessary,” which is no longer the case, said Dr. Rebecca Smith-Bindman, a professor of radiology, epidemiology, and obstetrics and gynecology at the University of California in San Francisco. “The truth is, now it’s ubiquitous. And many of these tests don’t need to be done.”

The question of risk remains a matter of fierce debate among radiologists: Some say that the amount of radiation used in diagnostic studies is safe and that the benefits far outweigh the small chance that a person will develop cancer. But other experts, including Smith-Bindman, say that while patients should never avoid scans that are medically necessary, excessive radiation doses and indiscriminate use of imaging pose a clear and demonstrable danger.

Studies published in 2007 and 2009 by teams at Columbia University and the National Cancer Institute predicted that up to 2% of future cancers — approximately 29,000 cases and 15,000 deaths annually — might be caused by CT scans. A 2011 report by the Institute of Medicine found that the two environmental factors most strongly associated with breast cancer were radiation exposure and the use of post-menopausal hormones.

While a single scan would rarely be concerning, many Americans undergo multiple tests, the Kaiser report notes. A 2009 study by researchers at Brigham and Women’s Hospital in Boston found that among 31,000 patients who received a diagnostic CT scan in 2007, 33% had more than five during their lifetime; 5% received 22 or more; and 1% underwent more than 38 scans.

A “decision support” system that creates a set of standards for doctors to follow, pioneered at Massachusetts General Hospital in Boston, reduced the rate of inappropriate imaging tests from 6% in 2006 to 1.5% in 2014, according to Dr. James Brink, the hospital’s radiologist-in-chief. A similar statewide program in Minnesota cut the growth rate from 7% per year to approximately 1% annually.

New Medicare rules will require doctors to consider appropriateness criteria developed by the American College of Radiology when ordering imaging. Beginning this year, Medicare will reduce by 5% reimbursement for CT scans performed on machines that fail to meet modern standards, including the ability to automatically adjust radiation doses.

But significantly reducing the number of unnecessary CT scans may be an uphill battle, the Kaiser report says. A recent study found that doctors who order numerous tests — a practice known as defensive medicine — get sued less often.

Financial incentives also fuel the casual use of scans. “Radiology has become an enormous profit” center for hospitals, Smith-Bindman said. “The amount we get paid is very high” under fee-for-service systems.

Source: Kaiser Health News; January 6, 2016.