Soaring CT-based radiation exposure points at self-referral

The U.S. population underwent seven times as much ionizing radiation exposure from medical imaging in 2006 as it did in 1987, mainly from CT, according to a study released at the 2009 National Council on Radiation Protection and Measurements in Bethesda, MD. Overutilization due to self-referral appears to bear some blame.

Findings of the NCRP report No. 160, released March 3, serve as follow-up to a preliminary report released in April 2007 that suggested the amount of radiation dose experienced by the U.S. public from such exams could have increased more than 600% in the last two decades.

In this year's study, NCRP researchers distinguished five different sources of radiation exposure to the U.S. population:
• background radiation
• medical procedures
• consumer products
• facilities
• occupational exposure


In the early 1980s, medical imaging accounted for 15% of the total radiation exposure, whereas more than 80% was due to background radiation. In contrast, investigators found that by 2006, background radiation accounted for no more than half of total radiation exposure, while medical imaging was responsible for 48%.

Collective effective dose from medical imaging accounted for 123,000 person-sieverts in the early 1980s. Researchers found the collective effective dose in 2006 had risen to 899,000 person-Sv, a staggering 630% increase.

"The increase was due mostly to the higher utilization of CT and nuclear medicine," said Dr. Kenneth R. Kase, NCRP senior vice president and chair of the scientific committee in charge of the report.

CT and nuclear medicine accounted for more than a third of the total radiation exposure and 75% of the radiation exposure due exclusively to medical imaging exams. An estimated 67 million CT scans and 18 million nuclear medicine procedures were performed during 2006, according to Kase.

Constant improvement and widespread use of accurate imaging technologies have brought about undeniable benefits for patients, according to the American College of Radiology. But study results also highlighted increasing concerns about imaging overutilization. At last year's International Congress of Radiology, NCRP executive director David A. Schauer noted as much as $16 billion per year is spent on unnecessary self-referred noninvasive diagnostic imaging. Self-referral was a primary driver of the radiation exposure increase, Schauer said in June 2008.

A Government Accountability Office report in June 2008 and peer-reviewed medical studies indicate that in-office CT, MRI, and nuclear medicine exams charged to Medicare from 1998 through 2005 grew at three times the rate of the same exams performed in hospitals and independent diagnostic testing facilities. Studies by private payers such as the Blue Cross Blue Shield organization indicate that nearly half of self-referred imaging is unnecessary.

Data only confirm the belief that imaging utilization goes through the roof when physicians are in a position to refer patients to a facility in which they have a financial interest, said American College of Radiology spokesperson Shawn Farley.

"By definition, any CT, x-ray, etc., that uses radiation that is an unnecessary test is an unnecessary exposure to radiation," Farley told "It's an easy connection of the dots."

Countless diagnoses are both made and excluded with medical imaging on a minute-by-minute basis worldwide. But these unquestionable benefits must be weighed against the exposure to ionizing radiation and its attendant risks, said Dr. James A. Brink, chair of diagnostic radiology at Yale University.

Device manufacturers and medical imaging experts are working together to reduce the radiation dose associated with medical imaging to levels that are as low as possible. Several novel approaches have already led to dose reductions that were not thought possible a short time ago, Brink said.

"Continued innovation promises continued use of medical imaging with lower and lower doses of ionizing radiation," Brink said.

Imaging experts have to lead efforts to ensure imaging studies are done appropriately and, at the same time, do everything possible to limit the radiation exposure both to adults and children, said Dr. Donald P. Frush, chair of the ACR Pediatric Commission and a member of the Alliance for Radiation Safety in Pediatric Imaging.

"All the Alliance organizations realized that it was important to address the fact that imaging utilization, including that affecting children, had gone up and that people weren't always using the appropriate technique," Frush said. "That's why we designed the Image Gently campaign to child-size CT plus other strategies that will further reduce dose."

The general public needs to understand that CT is not an evil part of medicine, but that it provides a beneficial component of healthcare for both the acute setting with its life-saving information and in less acute settings in the evaluation of other disorders and trauma, Frush said.

Tied to the increasing use of CT is the fact that radiologists can do things now that were impossible to accomplish medically two or three decades ago. Benefits and risks always have to be weighed out, however, he said.

"The science says we should be using CT more than we did 30 years ago," Frush said. "But many people would argue that we need to look carefully at whether the increased radiation dose is appropriate, and there are certain situations where it may not be."

For more information from the Diagnostic Imaging and SearchMedica archives:
CT-based radiation exposure in U.S. population soarsPanel recommends major changes in ACR policy governing patient radiation exposureU.S. physicians remain oblivious to radiation exposure risksPediatric CT must balance quality, safetyInterventionalists need better methods to track radiation exposureRadiation exposure during pregnancy demands well-informed patient managementHybrid imaging poses radiation exposure challengesNew CT technologies can reduce radiation dose, untenable fears.diagnostic>