Radiation Damage — What a Surprise

My father’s grandfather, Francis Colgate Benson, was a pioneer in the treatment of cancer with radiation. He became a surgeon before the turn of the (last) century. By the end of WWI he became fascinated with the new field of radiology and worked on curing cancer with radiation. He died before America entered WWII. There is no way of knowing for sure, but family lore — and logic — has it that he died from the long-term effects of radiation exposure. As did Marie Curie, it’s believed.

The pioneers of radiation didn’t realize the power they were working with and didn’t properly protect themselves from exposure. Thomas Edison and Nikola Tesla both reported eye irritation from exposure to x-rays and other radiation. By 1922 150 people had died from radiation exposure and skin cancers were being reported. Very soon, scientists developed protective gear for themselves and doctors.

And yet nearly 100 years later Consumer Reports features an article on Surprising Dangers of CT-scans and X-rays. What a surprise. Also, what a scare headline. Used sparingly, imaging using radiation often has a higher benefit than risk (as in mammograms). The question is, how much is too much?

We are all exposed to “naturally occurring radioactive materials and cosmic radiation from outer space,” states RadiationInfo.org. The average “background radiation” exposure we all get is about 3 mSv per year. A single chest x-ray emits about 0.1 mSv (equal to 10 days of background radiation). CT-scans can expose a patient to as much radiation as 200 x-rays. The Consumer Reports article claims that “recent research shows that about one-third of those scans serve little if any medical purpose. And even when CT-scans or other radiology tests are necessary, doctors and technicians don’t always take steps to limit radiation exposure.”

All of your radiation exposure accumulates over a lifetime. More exposure to radiation increases your risk for cancer. How much? We all have a 1 in 5 chance of having cancer without factoring in additional radiation. The role that x-rays and CT-scans play is a small role, but it is cumulative with other radiation exposures. It’s nearly impossible to say how much radiation exposure is too much. Cancer tumors take 5-20 years to develop. Therefore, minimizing exposure when possible makes sense.

DNA has some ability to repair itself after radiation exposure. Too little is known about that process – how does DNA repair itself? Can it recover from some types of radiation and not others? How much damage can it recover from is all unknown. For that reason, less exposure is better.

Ironically, radiation treatment for killing cancer can increase your risk of developing a different type of cancer later in life. Cancer.org has good information about the role of radiation and chemo cancer treatments in causing second cancers.

There are two main ways radiation can damage DNA inside living cells. Radiation can strike the DNA molecule directly, ionizing and damaging it. Alternately, radiation can ionize water molecules, producing free radicals that react with and damage DNA molecules. Courtesy Windows2Universe.org
There are two main ways radiation can damage DNA inside living cells. Radiation can strike the DNA molecule directly, ionizing and damaging it. Alternately, radiation can ionize water molecules, producing free radicals that react with and damage DNA molecules. Courtesy Windows2Universe.org

Another source of radiation? Your cell phone and home Wi-Fi. They are very low doses, but they are constant and where do you carry your cell phone? Probably in your pocket and you hold it to your head to use. There are are very few studies on Wi-Fi and cell phone risk. But the effect of radiation is cumulative. (See my earlier blog, Can Cell Phones Cause Brain Tumors? for more information on cell phone radiation.)

How does radiation exposure increase cancer risk? Radiation can either damage DNA directly or create free radicals within the cells that can in turn damage the DNA. The damaged DNA causes cells to act abnormally leading to cancer. (Other carcinogens such as tobacco and asbestos can create free radicals, too.) MedicalNewsToday has a good explanation for those who want more detail on the negative effects of radiation exposure to cells in the body.

A mammogram exposes a woman to 0.4 mSv (equal to about 7 weeks of background radiation). The National Cancer Institute (NIH) claims “the benefits of mammography, however, nearly always outweigh the potential harm from the radiation exposure.”

MRIs and ultrasounds are both possible imaging substitutes for CT-scans. Neither use radiation and have no known long-term effects. But they have limits — ultrasounds are blocked by bones and MRIs can take 45 minutes, which is too long in an emergency. CT-scans generally give the clearest, most complete picture and for those reasons sometimes CT-scans are necessary. The exposure to radiation is probably not a reason to not get a CT-scan if your doctor is recommending one. If you have a condition that is causing you to have a lot of imaging done or you  are otherwise concerned, RadiologyInfo.com has a printable Medical Imaging History sheet (pdf) to help you keep track.

Check out Choosing Wisely, which offers lists compiled by medical associations on when patients should question tests such as CT-scans.

As always, I suggest you simply talk to your doctor to discuss the risks and the benefits of any procedure or medicine. Your doctor will give you great advice, but ultimately, your medical care is in your hands.

Suzanne B. Robotti

Suzanne Robotti founded MedShadow Foundation in 2012. Learn more about Su and her mission.

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