Avoiding Unnecessary CT Scans

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Jack Hollingsworth / Corbis

A patient undergoes a CT scan.

If you fall down and break something, they will take an X-ray at the emergency room. Show up with belly pain or breathing trouble and the same kind of X-ray — what we call a plain film — will usually be done. The reason we like plain films so much is that they're fast, easy, cheap and effective — and they expose patients to very little radiation. So little, in fact, that it's extremely hard (some experts say impossible) to demonstrate statistically that the radiation from an X-ray increases your risk of cancer. There's no question that X-rays can cause cancer, but the effect is so slight that it's hard to show — rather like proving that one piece of candy causes cavities.

Thirty years back we used plain films to diagnose nearly everything — appendicitis, kidney stones, pneumonia, broken bones — and an X-ray alone was enough. We took care of them all just using plain films. Today, however, there's a good chance that after ordering up that plain film, the emergency doctor will send you down the hall for a second test — one that exposes you to many hundreds of times the radiation of a plain film: a CT scan. The radiation from a CT scan, or computed tomography, actually has been shown to cause cancer — quite a bit of it. A recent report, published in November in the New England Journal of Medicine suggests that the radiation from current CT-scan use — estimated at more than 62 million CT scans per year in the U.S. (up from 3 million in 1980) — may cause of as many as 1 in 50 future cases of cancer. It's a serious charge.

So, who is to blame? Well, you can start with the Beatles.

That's right. It was the sizeable profits from the Fab Four's record sales that a company called EMI (Electric and Musical Industries) invested in research, which led to the first commercially available CT scanner in the early 1970s. CT was a huge plus: It could image so many things in the body that were difficult, painful or simply impossible to see otherwise — brain tumors, spine problems, problems in the liver or lung. Nevertheless, in the '90s, CT scans were largely upstaged by the vastly more complex — but radiation-free — MRI scan. Overall, few docs would disagree that the MRI is a better test. Except for being somewhat less sharp when looking at bone, MRI is clearly more sensitive and versatile. But CT scanning has made a huge comeback in the past five years. Almost every office day of late Iíve gotten new patients who have had CT scans in the emergency room — scans that I don't really need to treat them.

At least one reason for the overuse of CT is certainly financial. Major insurers still pay fairly well for the scans. While it's true that advanced technology has made CT machines better, faster and more affordable over the years, the only thing that's really different now versus five years ago is that more hospitals are going bankrupt — they need to be a lot keener at making money to survive. So, for starters, they're hiring doctors: The hospital pays them a salary while billing for the services they order or perform. (Doctors in private practice, unlike hospital-employed doctors, work in but not for the hospital.) Hospital-employed docs must earn their keep. And ordering CT scans is a good way of doing that: Since the exact reasons (what we call the "indications") for ordering a CT scan in a given medical situation are often vague and fudgeable, it's hard to claim they're over-ordered. The cancer caused by a CT scan doesn't generally show up for decades — and there are all sorts of other intervening reasons why a patient would develop cancer — so no one is too scared of getting sued for ordering a CT scan. Getting sued for not ordering one is more likely. So, the people who should be the most worried about CT scans are the patients.

We fret about many problems which, in cold, statistical terms, are quite unlikely ever to occur. The actual likelihood of dying from smoking, not wearing seatbelts or sunscreen, eating preservatives or biking without a helmet is relatively low. Our parents' generation, after all, (mostly) survived the clutches of these and many other perils. But while we generally heed the warnings about cigarettes, seatbelts and sunscreen, we go on having CT scans without putting up the slightest fuss. CT is a controllable risk. Doctors can practice medicine very well, most of the time, without CT scans. We need to avoid them when we can.

The question is, can truly rational decisions be made regarding their use? The statistics are hard to calculate. It would take all the computers at the Mayo clinic to compare the real risk to your life of doing a CT scan in a given situation with that of not doing one. And if the doctor can't compute that risk, there's no real way that a second-guessing patient can. But you can, and should, be more than a little reticent to have a CT scan unless it's absolutely needed.

CT is absolutely necessary with head trauma and acute abdominal conditions. Minutes can make a difference in these cases — if, say, there's bleeding around your brain and you can't get an MRI — and the speed of a CT scan makes it worth the risk. But in most other situations, it's wise to let the doctor convince you it's worth it, before consenting to the scan. Ask your doctor what decisions he or she plans to make with the information from the scan. What other tests could yield the same information? Would an MRI be better? Ask why the CT scan is necessary right now. Make a phone call, ask a specialist. Ask how confident the doctor feels about your diagnosis without the scan. If a good surgeon really thought I had appendicitis, I'd go straight to the OR — not to the scanner.

But the reality is that in some cases, you'll need a CT scan. If so, just remember that for you to be there, breathing, you've already beaten the odds of sickness and death any number of times. And you'll probably beat the CT-cancer odds too. If the doctor's answer to your questions, however, is something like "Well, why not do a CT scan?" or "A CT scan would show it too" or "A CT scan would rule out something rare" my response would be "Why not skip the scan?" One in fifty cancers is a hard number to ignore.