symposium

0 Comments | Insight on the News, July 23, 2001 | by Robert J. Cihak, | Michael A. Glueck, | Robert J. Stanley

Q: Are whole-body CT scans safe and effective for exploratory screening?

Yes: In the real world, the X-rays used in these examinations are extremely safe.

So-called CT (computed tomography) X-ray examinations have been available for three decades. Several years ago, some radiologists started offering these examinations for "screening" of the chest and abdomen and/or other body parts to detect disease before symptoms occur. This procedure is known as a "whole-body" CT scan. The hope is to identify problems early, when treatment can be most effective.

In contrast, "diagnostic" examinations are done to identify or exclude medical conditions suspected because of other findings, such as a lump or a pain. The same examination, for example CT of the lungs, might be done for either screening or diagnostic purposes.

Through the years the quality, cost, availability and usefulness of CT examinations continuously improved. A single CT scan examination now can show fine details in many parts of the body, such as the lungs, arteries, kidneys and bones.

Screening CT examinations are not yet available on every street comer, although Newport Beach, Calif., has two facilities. California leads the country with at least five installations clustered around the Los Angeles area; additional facilities are located in Arizona, Florida and Maryland. CT Screening International LLC, with corporate offices in Irvine, Calif., currently has two sites operational in California with 11 additional sites on both coasts opening this year, according to Phil Voluck, the firm's president.

Just when you realized it was safe to drink the water after the recent arsenic scare, Food and Drug Administration (FDA) officials are taking their turn to cry, "Wolf!" They struck recently with alarmist comments about hypothetical radiation dangers and health risks from screening whole-body CT scans, as reported in a front-page Los Angeles Times article.

Scared people literally are stopping us in the streets with questions. Judy Slutzky of Newport Beach told us, "When I read the article, I canceled my scan appointment." As retired radiologists, we're concerned about patients' unfounded fears.

The current scare is based on the May 17, 2001 report of Thomas B. Shope Jr., Ph.D., an FDA official, to the FDA Technical Electronic Product Radiation Safety Standards Committee. Shope has a vision of "safety" lacking a balancing vision of possible benefits. At the meeting, Dr. John F. Cardella of the State University of New York, Syracuse Health Science Center, and a member of this advisory committee expressed concern about the lack of "oversight" and "checks and balances" in screening CT. FDA officials did not present balanced information about the benefits of low-dose X-rays.

The one-sided statements about X-rays reported in the Los Angeles Times are not the reporter's fault. We've all seen scare stories about radiation from X-rays and nuclear-power plants. The beneficial or benign effects of low doses of this radiation are not nearly as newsworthy as the very rare accidental injury or death from these invisible rays. Also, vested interests in the "radiation phobia" business suppress scientific good news.

You've probably never heard of the "Nuclear Shipyard Workers Study" conducted by researchers at Johns Hopkins University; the health of workers exposed to low doses of radiation from working on nuclear-powered ships was compared with the health of workers doing similar work on non-nuclear ships. A preliminary 1991 report on the data accumulated in this multimillion-dollar study found that workers receiving low radiation doses had significantly lower death rates and generally were healthier than workers not getting a small extra dose of radiation. Despite millions of taxpayers' dollars paying for the research, this good news has not yet been released in a formal scientific article.

Many other studies and experiments have been done, summarized at http://cnts.wpi.edu/rsh. Some of the good news from recent scientific work includes the following:

* A single unit or photon of X-ray or other radiation won't hurt you or cause a body cell to become a cancer, just as a single aspirin tablet won't poison you.

* When radiation doses are spread out over time instead of received all at once, the body tolerates more radiation without harm, as it does with other agents, such as aspirin. We take one-quarter of an aspirin tablet every day to decrease our risk for heart attack and stroke. But if we took 100 tablets at a time, we'd die of aspirin poisoning. We're sure we've taken several thousand aspirins during our lifetimes, and we're not dead yet!

* Low radiation doses enhance health, as do low doses of vitamins, aspirin and many minerals. Radiation doses of less than 0.25 Seivert per year (in other common units, roughly 25 rad or 25 rem) are well inside this range. This is twice the level of most screening CT examinations. Although the degree of health enhancement still is controversial in some circles, modern scientific evidence demonstrates the safety of low-dose radiation.