Full-body CT scans - widely promoted in advertisements as a way to give yourself peace of mind - produce 1000 millirads of gamma radiation per full body scan and frequently find harmless abnormalities that lead to invasive, anxiety-producing follow-up tests. Additionally, they may be a waste of money for patients under 40, who run a low risk of serious disease.

"This got pushed to the public before any of the research was done," said Dr. Giovanna Casola of the University of California at San Diego. "They're saying do it for your peace of mind, do it for your wellness, for your family. Nobody's saying, 'Half the time we're going to find things that you' re going to worry about,"' sometimes needlessly. An worst of all its ionizing, cancer inducing radiation that could cause more cancer than it finds.

Widely Promoted Scare
The increasingly popular scans - widely promoted in radio and TV ads and on billboards - give doctors a view into the body from the neck to pelvis with CT scan machines. The scans typically are offered at private, for-profit centers, cost several hundred dollars or more and usually are not covered by insurance.

Dr. Casola and her colleagues studied 1,192 patients ages 22 to 85 who had full-body scans at private, for-profit imaging centers and recently presented their findings at the Radiological Society of North America's annual meeting.

Forty-six percent of the scans showed abnormalities, most in the lungs, kidneys or liver. About 25 percent of those were suspected cancer; 15 percent were other significant ailments such as emphysema; and just 1 percent were strongly believed to be cancer or some other life-threatening disease. Thirty-seven percent of the participants were advised to have follow-up tests.

No one under 45 had scan results that strongly suggested cancer, and patients younger than 40 had very few findings requiring further tests, Casola said.

Other research has shown that follow-up tests usually determine that scan-detected abnormalities are insignificant. Casola said that is probably the case with many of the study participants, though data on subsequent testing generally was unavailable.

"Many of these for-profit centers don't follow up on their patients to see what happens to them," she said.

Most people in Casola's study got the scans on their own and were not referred by their doctors. Many physicians are skeptical of the scans because they have not been well-studied, said Dr. Stephen Swensen, the Mayo Clinic's chief of radiology. Swensen said people should not have the scans unless they have consulted their own doctors and are referred by someone who doesn't have a financial interest in the tests. "There's no medical society in the world that recommends this."

May Provide False Sense of Security
And the scans are not foolproof either. Judie and John Roth of Morris, Ill., discovered that about a year ago when they gave each other full-body scans as anniversary presents. Results for both turned up nothing suspicious, but a month later John Roth, an obstetrician-gynecologist, was diagnosed with bladder cancer.

"It was just kind of a shock," said Judie Roth, 60. "I didn't get any really good answers when I called the scan people back," she said. "What they pretty much said was, maybe because of the size of the tumor" it was missed.

Radiation Risks
With the increased use of X-rays, the federal government has begun evaluating whether medical X-rays should be declared a carcinogen. This move could help curb the exposures and force doctors to pay closer attention to the risks. The study's report will be listed in the National Toxicology Program's 11th Report on Carcinogens expected in 2004.

The National Cancer Institute says the use of CT scans, like those use by AmeriScan™ and others, has increased sevenfold in 10 years. Of particular concern is the exposure in children. For every 1 million children scanned with CT, an estimated 1,500 will develop cancer two decades later.

One can't help noticing when the X-ray technician dashes for shelter behind a leaden window, before flicking on the X-Ray machine, that there must be significant risk of radiation from the test. It seems ironic that the technology being promoted so freely to save lives is also a well-established cause of cancer.

In most of the cancer literature, radiation is conveyed as an almost negligible concern. However, "Now that the benefits of mammography have begun to be cast in greater doubt," says Cindy Pearson of the National Women 's Health Network, in Washington, D.C., "those risks may also need to be better defined. Is there a level below which it is reasonably safe? They've never answered this question," she says.

That's because scientists have never been able to show what an absolutely safe dose is, says Barry Kramer, senior medical scientist in the cancer prevention division at the National Cancer Institute. "There is no doubt that X-rays cause cancer; it all boils down to your dose."

Dr. Samuel Epstein, a professor of environmental medicine at the University of Illinois at Chicago School of Public Health, argues that the radiation risks of radiation are notoriously underestimated.

To help protect women, the Food and Drug Administration limits the amount of radiation that X-rays can deliver to women's breasts to 300 millirems (a unit for measuring absorbed doses of radiation) per film per view, says Kramer. Even with that restriction, Epstein says, women receive too much radiation. Radiologists routinely take two films per breast.

To put this in perspective, says Mary Helen Barcellos-Hoff, a radiation biologist at Lawrence Berkeley Laboratories in San Francisco, the average American gets about 360 millirems of radiation annually, from natural background radiation coming from rocks, radon and cosmic rays, as well as man-made sources." One stroll through an airport scanner causes 2 millirem of radiation exposure, a cross-country airplane trip will cause 5 millirem, a full dental X-ray causes 350 millirem, and an MRI can produce 6000 millirem.

Take Away 3 Years of Your Life with every Full-Body Scan
A full-body scan produces 1000 millirem of radiation. That is equivalent to 3 years worth of typical background radiation exposure. Add that to the 1200 millirem of radiation a woman gets from an annual mammogram and you can see how the risk adds up. Dr. Epstein estimates that every 1000 millirem of radiation exposure increases a woman's risk of a breast cancer by 1 percent. If a woman gets an annual mammogram plus an annual full-body scan she will increase her risk of breast cancer by 25% every 10 years. If men start getting annual full-body CTscans, we will likely see radiologists finding more testicular cancers and saying, "See, if we had not done that CT scan, we would not have found that tumor we caused." That does not sound like smart preventive care to me.

Radiation Measures Defined

• Rad: Or, Radiation Absorbed Dose recognizes that different materials that receive the same exposure may not absorb the same amount of energy. A rad measures the amount of radiation energy transferred to some mass of material, typically humans. One roentgen of gamma radiation exposure results in about one rad of absorbed dose.
• Rem: Or, Roentgen Equivalent Man is a unit that relates the dose of any radiation to the biological effect of that dose. To relate the absorbed dose of specific types of radiation to their biological effect, a "quality factor" must be multiplied by the dose in rad, which then shows the dose in rems. For gamma rays and beta particles, 1 rad of exposure results in 1 rem of dose.