Should I Get that CT Scan?

Barely anyone goes to the doctor and begs for a CT scan. But neither do most people beg not to have one. I, however, do. My family is riddled with cancer, with practically everyone having had one form or another, especially as they get older. The link between radiation from a CT scan and cancer is undoubtedly controversial, but for me it's always been a natural leap. Avoiding them, unless absolutely necessary, is my mantra.

Never was my anti-X-ray posture more apparent than when my family was in a car accident one summer night a couple of years ago. We had swerved from a deer, sped off road and, like some monster-car roller coaster, bounced up and down grassy hills as high as six feet tall. When the car finally crashed to a halt, the impact of the airbag broke my sternum. But it was my daughter who suffered a worse fate. She had compression fractures in seven vertebrae, including one in her neck.

Right now, the folks who say radiation is indeed risky make a compelling case and have data.

That night in the ER, lying on a gurney, and unable to move, I steadfastly refused to allow my daughter to have a CT scan. (She was walking about, ministering to me, and in really good cheer. Was a high-powered zap really necessary?)

I practically begged every doctor to hold off, reminding them of a national campaign, Image Gently, initiated by Society for Pediatric Radiology among others, that urges doctors to use CT scans on children prudently (an analogous campaign for adults is called "Image Wisely").

I did triumph, and my daughter wound up with an MRI (which uses magnetic fields and radio waves instead of a series of X-rays to make detailed images) rather than a CT scan, something that, for me at least, made the bitter pill of her fracture diagnosis easier to swallow

Why was I so insistent about not exposing my daughter to a CT scan? Why did I, with zero medical training, eat up time in the face of an emergency trying to negotiate with the experts? You're probably thinking that I'm horribly irresponsible or some kind of radiation-phobic, extremist nut.

Actually, I'm hoping that you would do the same in a similar situation — and why I delved into CT scans in my book, "Health Your Self." Below is an excerpt:

Zap Me If You Can

The radiation from CT scans is, for lack of a better word, humongous.

CT scans to the chest, for example, deliver the equivalent of as much as 400 regular chest X-rays or 1,500 dental X-rays so quickly that patients barely know what hit them. CT scans to the brain are equal to as much as some 500 chest X-rays. MRIs on the other hand, emit no radiation at all.

Nonetheless, CT scans today are performed more than 85 million times each year. It's no wonder. Their crisp, detailed three-dimensional visualization of our insides help physicians diagnose maladies from brain tumors and strokes to rare cancers and kidney stones in a non-invasive, painless way that spares patients exploratory surgery — something common a generation ago.

If you haven't yet surmised, the reason these super-charged doses of radiation are potentially worrisome, and not just to me, is their possible link with developing cancer.

There's no doubt that the link between X-rays and cancer is something of a controversial area.

There are researchers who dispute that CT scans cause enough cell damage to result in cancer. They argue that the body is equipped to repair whatever injury is wrought by a hit with radiation in the same way it repairs other assaults to the inner workings of our cells, like oxidation, that occurs by, well, breathing. These experts say that patients can have many X-rays, but it's not until the number goes beyond a particular threshold of exposure that irreparable cell damage will occur — and that this threshold is high enough that most of the population need not worry.

We'll probably know more definitively about radiation's link with cancer in the years ahead as more study results roll in. But right now, the folks who say radiation is indeed risky make a compelling case and have data. That's what makes it reasonable to proceed as if radiation could be a problem.

Researchers from the Radiology Outcomes Research Laboratory estimate that up to 5% of all future cancers will be attributable to exposure to medical imaging.

Every day we are bombarded by natural, background radiation that we can't escape. It comes from sources such as the sun, and the environment generally.

Then there is the radiation from medical imaging. Unlike background radiation, when we are exposed to ionizing radiation from X-rays, it is a deliberate act. Fully half of all the radiation we are exposed to in our lifetimes is from doctor-ordered tests; the other half, background radiation, we can't avoid.

Should I Get that CT Scan?

During an X-ray, ionizing radiation is absorbed by tissues in order to get an image. At that moment, the strands of DNA inside your cells may get injured. Sometimes the injury is just a nick, other times it's a full-fledged alteration of your DNA.

With smaller doses of radiation, most likely just one of DNA's double strands is ensnared. If that strand is damaged, the strand right next to it will act like a template for repairing the damaged strand.

With larger doses, meaning CT scans, two strands or clusters of strands can get bollixed up, sometimes breaking altogether. Luckily, our body usually rallies; it brings out its army of repair mechanisms that can get DNA back into shape. Sometimes your body just kills off the hapless, miscoded cells.

Sometimes, though — and this is what to worry about — the repair process itself is error-prone, and the DNA's underlying code is damaged with small deletions and other alterations. That's known as a mutation, which is exactly what triggers the process that leads to cancer.

Rita F. Redberg and Rebecca Smith-Bindman, researchers from the Radiology Outcomes Research Laboratory at the University of California, estimate that up to 5% of all future cancers will be attributable to exposure to medical imaging.

CT Scans and Children

Kids are the hardest case to justify scanning. They are more vulnerable to harm from radiation than adults for two reasons.

First, cancer takes a long time to develop. It could take as few as five years, but usually around 20, and sometimes as much as 60 years to appear. So, if a child has a scan that causes an error in underlying DNA code, then he or she could see the effects as a young adult or in middle age. A 65-year-old who gets scanned might not live long enough to experience the resulting cancers.

The other reason is that kids are still growing, and a higher proportion of their cells are what's called stem cells, literally mother of all cells, and their progeny, called "daughter cells," inherit any errors in their mutated code.

A seminal study in 2012 in The Lancet looked at more than 175,000 British children and found that the kids who received CT scans had three times the risk of developing leukemia and brain cancer within 10 years. These are very uncommon cancers to begin with, so that's a relief. But the fact that CT scans can so significantly raise their incidence, and in a relatively short period of time, triggered concern in the medical community.

CT-scan manufacturers are constantly trying to lower the radiation dose of their machines and providing new software for older machines. This is very encouraging news, yet a standardized, regulated dose for imaging doesn't exist.

What Can You Do?

Deciding what to do about all this isn't as difficult as it may seem.

First of all, you should absolutely get a CT scan if a doctor can convince you that the benefits outweigh the risks. Worthy reasons would include a head injury so severe that you're knocked unconscious or so confused you can't string a sentence together. Or long-term, ongoing symptoms, like headaches and seizures, that may suggest a brain tumor.

Even if a CT scan appears clinically justified, make yourself part of the discussion.

Always ask if a different type of imaging, like an MRI, which makes use of radio waves and magnetic fields, or sonogram, which uses high-frequency sound waves, would do an equally good job or at least a good enough job. Or if a few conventional x-rays will suffice.

To bolster your own credibility, mention that your view is backed by professionally endorsed groups like Image Gently and Image Wisely.

What you can do is stay fully aware, and don't be shy. You must start a dialogue with your doctor, so they know they have a smart patient in his office.

If you find that you have no choice and must have a CT scan, you can still protect yourself.

If you are on the thin side, a lower dose of radiation is required for the energy to pass through your body. Be bold and remind the technician to make sure the settings are adjusted to accommodate you, especially for older machines that may not automatically do this.

For the children in your life, try to find a pediatric hospital or a hospital with a pediatric wing to perform the scan. If you bring a child to a hospital's ER that just scanned 20 adults, the machine may be programmed for grownups and there's a good chance no one is thinking about reducing the dose for a kid.

Here are other things to watch out for: If a doctor orders a CT scan and the scanner is in their office, this poses a conflict of interest. You just don't want that kind of motivation entering the picture and should get a second opinion before you climb in.

Another common practice among doctors is to order their own scan, even if you've already had one. You should always be sure to get copies of all your previous scans — not just the written report, but an actual digital copy — and inform your doctor that you have them at the ready.

What you can do is stay fully aware, and don't be shy.

You must start a dialogue with your doctor, so they know they have a smart patient in their office and hopefully you will get the physician thinking twice about that test they might have ordered up without thinking too hard in the first place.

ShareNext Avenue on FacebookNext Avenue on TwitterEmail Next AvenueJanice M. Horowitz, author of "Health Your Self," is a former veteran Time magazine health journalist who created and hosted the public radio segment,"Dueling Docs: The Cure to Contradictory Medicine." She has also contributed to The Economist, Allure and The New York Times. Read More