FAQ: whole-body scans

Skeptical doctors sometimes refer to CT (computed tomography) screening exams as "whole-body scams." The high-priced scans examine a person from head to toe, searching for early signs of disease. The following information will tell you more.

No one. CT scans sound like the stuff of science fiction novels — and many doctors say that's where these tests belong.  No major medical organization recommends whole-body scans that are offered by clinics as one-stop screening for cancer, heart disease and other conditions. A CT scan produces cross-sectional images of internal organs by passing X-rays through tissue at hundreds of different angles. These high-tech scanners have an important role in medicine.

However, most doctors say there is no way to justify the heavy dose of radiation a patient receives during a whole-body scan, given the test's questionable value. If you have a whole-body scan, you will probably receive scary news: "We found a suspicious mass." A study published in the journal Radiology estimated that nearly 91 percent of people who undergo whole-body scans have at least one positive test result. However, the vast majority of these ominous images turn out to be meaningless.

The human body is full of benign nodules, clumps of scar tissue and other harmless bumps and blobs that may turn up on a whole-body CT scan. A minuscule two percent of people who test positive actually have a disease. Worse, whole-body scans may miss potential problems, so a clean test could cause a false sense of security.

Are CT scans overused? Some scientists say yes. After all, radiation harms cells, and CT scans expose the body to a sizable dose. For example, a CT scan of the abdomen produces at least 50 times more radiation than an X-ray. Exposure to large amounts of radiation causes a small but significant increase in the risk of cancer, particularly leukemia and cancers of the breast, lung and thyroid.

The threat of cancer to someone undergoing a single CT scan is small, but people with conditions such as kidney stones and cancer may undergo repeated CT scans. The authors of a study published in the New England Journal of Medicine estimated that CT scans might cause up to two percent of cancer cases in the United States.

The authors of the study point out that the benefits of CT scans in medicine far outweigh the risks, but they argue that up to one-third of CT scans may be unnecessary. If your doctor says you need a CT scan, consider asking if another imaging method, such as MRI or ultrasound, would provide similar information. If you have a CT scan and you're given a copy on CD, don't lose it. It may help you avoid having a repeat scan.