Friday, November 10, 2006

Worries Mount Over Excessive CAT Scans

When we undergo CT scanning, we don’t normally realize that we expose ourselves to harmful radiation. Some doctors began to observe that excessive CAT scans could create a really harmful situation.

There haven't been any studies that directly examined whether people who had multiple CT scans went on to develop cancer. But as the number of CT scans has climbed, some doctors have started to take notice of individual patients who have received multiple scans that place their total radiation doses at levels near or beyond those of some survivors of the nuclear attacks on Japan in World War II. Residents of Hiroshima and Nagasaki received a mean dosage of 20 millisieverts, a measurement of radiation exposure, although the bomb survivors received all the radiation at once, which is thought to be riskier, and the type of radiation was different from the X-rays used in modern medical scans. According to a managed-care database, one patient received 341 CT scans over an 18-month period, bringing the radiation exposure to 992.24 millisieverts. Several other patients received more than 100 CT scans.

There's been an explosion in CT scanning in recent years. Scans increased by nearly 50% between 2000 and 2003, when they hit 57 million. The rise comes from rapidly advancing CT technology that gives doctors better, more-detailed information to work with, making the scan widely viewed as one of the most valuable diagnostic tools in the field. What's more, the test is noninvasive and typically doesn't cost anything for insured patients. The test has also become popular as a means for patients to get full-body scans as a check-up.

Now, a range of players in the field are moving to prevent runaway CT scanning, including a large managed-care organization and the nation's largest diagnostics-benefits manager. And General Electric Healthcare has come out with a device that reduces radiation during cardiac CT scans by as much as 70%. "Obviously, the concern is the increased risk related to cancer," says Arl Van Moore, chairman of the American College of Radiology, which is also looking at the issue. Dr. Moore recently appointed an ACR task force to examine the issue of radiation exposure from diagnostic imaging. The group's report and position statement based on its findings is expected to come out next year.

Invented in the 1970s, computed axial tomography scans (called CAT or CT scans) use special X-ray machines to take images of the body from multiple angles and can show various types of tissue with detailed precision. But unlike other kinds of advanced images, such as MRIs and ultrasounds, CT scans take pictures using ionizing radiation.

A full-body CT scan measures an estimated 12 millisieverts to 25 millisieverts. A mammogram measures about .84 millisieverts. We get about 3.6 millisieverts a year from natural sources. A 10-millisievert level is associated with an increased risk of cancer, though health experts debate whether a one-time dose carries different risks from those of cumulative exposure.

Children are at the greatest risk for long-term health problems from radiation because of the damage it wreaks on developing cells. In 2001, the Food and Drug Administration put out a notice to health-care professionals emphasizing the need to try to minimize radiation exposure in pediatric patients.

Not everyone in the medical community is embracing the cause. Some feel the risks aren't well-established and that the concern could dissuade patients from getting necessary tests. Reuben Mezrich, professor and chairman at the University of Maryland School of Medicine's Department of Radiology, casts a skeptical eye on the issue, saying there haven't been enough good studies on the risks. He also isn't convinced that radiation accumulates over time, noting that "we're always getting radiated."

Still, the nation's largest diagnostics benefit manager, National Imaging Associates Inc./Magellan Health, is taking steps to rein in CT scanning. In August, NIA started a new procedure with 30 of its clients to flag excessively scanned patients. NIA alerts their doctors and initiates discussions to see if there are other diagnostic options. Also, doctors who call insurance companies for pre-authorizations of patients deemed excessively scanned will need to talk to NIA first.

Company vice president and founder Thomas Dehn, a radiologist, says that the company started developing the program after seeing radiation-exposure levels that were 1,000% higher than medical guidelines, which Dr. Dehn calls "extraordinary, inappropriate and alarming."

At the same time, these Insurance companies won't let patients to undergo MRI because of the cost involved. A move away from CT scans won't necessarily save money. But, a reduction in overall scanning would save payers on insurance costs. Also doctors could instead shift to other technologies such as MRIs, which don't emit ionizing radiation.

Radiation by the numbers:

Type of Procedure and Estimated Dose

Chest X-ray => 0.01-0.1 millisieverts
Mammogram => 0.8 millisieverts
Head CT => 2 millisieverts
Chest CT => 8-10 millisieverts
Abdomen-pelvis => 10 millisieverts
Full body screening => 12-25 millisieverts
World War II Atom Bomb (mean) => 20 millisieverts

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