Too Much X-ray or CT Scan can Kill You!

By Marilyn Marchione, AP Medical Writer Marilynn Marchione,
Ap Medical Writer – Mon Jun 14, 10:59 am ET

We fret about airport scanners, power lines, cell phones and even microwaves. It's true that we get too much radiation. But it's not from those sources — it's from too many medical tests.

Too much radiation raises the risk of cancer. That risk is growing because people in everyday situations are getting imaging tests far too often.

Of the many ways people are overtested and overtreated, imaging is one of the most common and insidious. CT scans — "super X-rays" that give fast, extremely detailed images — have soared in use over the last decade, often replacing tests that don't require radiation, such as ultrasound and MRI, or magnetic resonance imaging.

Radiation is a hidden danger — you don't feel it when you get it, and any damage usually doesn't show up for years. Taken individually, tests that use radiation pose little risk. Over time, though, the dose accumulates.

Doctors don't keep track of radiation given their patients — they order a test, not a dose. Children and young women, who are most vulnerable to radiation harm, sometimes get too much at busy imaging centers that don't adjust doses for each patient's size.

How much radiation is risky?

It's hard to say. The best guess is based on the 1986 Chernobyl nuclear power plant accident and studies of Japanese atomic bomb survivors who had excess cancer risk after exposures of 50 to 150 millisieverts (a measure of dose) of radiation.

A chest or abdominal CT scan involves 10 to 20 millisieverts, versus 0.01 to 0.1 for an ordinary chest X-ray, less than 1 for a mammogram, and as little as 0.005 for a dental X-ray. Natural radiation from the sun and soil accounts for about 2 millisieverts a year.

A study by Columbia University researchers, published in 2007, estimated that in a few decades, as many as 2 percent of all cancers in the U.S. might be due to radiation from CT scans given now. Since previous studies suggest that a third of all tests are unnecessary, 20 million adults and more than 1 million children are needlessly being put at risk, they concluded.

Just because a scan didn't find anything wrong doesn't mean a test wasn't needed. Scans are useful for many diagnoses. But many studies suggest people are getting too much imaging now.

Reasons for overuse:

_Accuracy and ease of use. Scans have become a crutch for doctors afraid of using exams and judgment to make a diagnosis. Some think a picture tells more than it does.

"Physical therapy for an orthopedic injury is always the first choice," yet doctors rush to order tests, he said. "The question you should be asking when you do sophisticated imaging is, 'Is there something I can fix with an operation?'"

_Malpractice fear. A missed heart attack or a burst appendix could be devastating for a patient — and mean a lawsuit.

_Patient pressure. People urge doctors to "do something" to figure out what's wrong, and "often, doctors feel that the way to demonstrate that they're doing something is to order tests.

_Health care chaos. One doctor may not know that another has ordered the same test. If a patient is referred to a specialist, "it's often easier for him to order another study than to figure out how to get the one that was done somewhere else.

_Insurance issues. X-rays often are required by insurers to prove health, or for students to study abroad.

_Availability. Rural hospitals may not have an ultrasound technologist on duty in the wee hours, but imaging machines are always there.

_Treatment choice. A quick fix for chest pain — artery-opening angioplasty — requires far more imaging and radiation than bypass surgery does. The same is true of "virtual colonoscopy" instead of the standard version.

Which tests are overused?

A scientific group, the International Commission on Radiological Protection, cites routine chest X-rays when people are admitted to a hospital or before surgery; imaging tests on car crash victims who don't show signs of head or abdominal injuries; and low-back X-rays in older people with degenerative, but stable, spine conditions.

Even when tests are justified, they often include more views than needed and too much radiation. Top offender: chest CT scans looking for clogged arteries and heart problems. Cardiologists are increasingly aware of this risk and are seeking solutions.

What should patients do?

"You should question everything — what's the dose, why am I getting it? You should be an informed consumer.

Questions to ask about radiation scans:
_Is it truly needed? How will it change my care?
_Have you or another doctor done this test on me before?
_Are there alternatives like ultrasound or MRI?
_How many scans will be done? Could one or two be enough?
_Will the dose be adjusted for my gender, age and size? Will lead shields be used to keep radiation away from places it can do harm?
_Do you have a financial stake in the machines that will be used?
_Can I have a copy of the image and information on the dose?

Consumer information: radiology.com