This is not new news - it has been known practically from the time they were first made by Wilhelm Roentgen in 1895. Thomas Edison, inventor of the light bulb, had a research assistant who died following his exposures to x-rays leading Edison to say, "don't talk to me about x-rays, I'm afraid of them." During WW1 field x-ray injuries were so frequent that physicians were forced to address the problem.
For many years, doctors believed that any x-ray dose that did not cause reddening of the skin was safe. Then Dr. Alice Stewart in the 1950's and Dr. Rosalie Bertell in the 1960's, working independently and in population health studies, discovered that x-raying a pregnant woman doubled the risk of leukemia in the baby. It took twenty years before lead aprons and shields became standard cover for unexposed parts of the body in all x-ray facilities including dental offices.
So why, in 2014 do we have patients demanding x-rays (or CAT scans- more sophisticated x-rays) for the most trivial of reasons? And why do physicians order them under the same trivial circumstances?
The actual taking of an x-ray seems like nothing. The technician arranges us on the table or in the chair and steps back. We are asked to "hold our breath" or "bite down". We feel nothing. It is over - whatever it was - in seconds. Aside from the tech standing behind a screen, nothing suggests anything dangerous.
During that "nothing", waves of energy are emitted by electrons that become "excited" by electricity. Machines focus the waves so that they pass through us and land on a photographic sheet (or digital equivalent). Great way to identify broken bones or the roots of abscessed teeth.
The actual passage of the x-ray through the human tissue leaves a path of ionized molecules. Herein lies the danger. Ions are broken bits of their former selves. They are electrically charged. Molecules or atoms that are electrically charged try to become neutral again. They seek their opposite. If they are positively charged, they will seek a negatively charged ion and vice versa. The ionized molecule can be an enzyme, a cell membrane, or even a DNA molecule (the basis of life).
Almost all of the time the reconnection between positive and negative ions is benign. There is no way to identify the ones that are not - and, were you to kill someone with x-rays it would be the perfect crime. It would be many years, long after the x-ray itself is forgotten, that the badly reconnected ions developed into cancer - or other diseases (auto-immune diseases, high blood pressure, heart disease). Furthermore, there could also be no connection between the person's TB screening in the 1950's and their cancer in the 1980's. Frankly we don't know.
The American Cancer Society flat out admits that x-rays cause cancer. Another site lets you calculate your personal additional risk. http://www.xrayrisk.com/calculator/calculator-normal-studies.php
What to do? In the emergency room last week, a young woman questioned me about the x-ray that I had ordered for her child. She was totally right to do so. No matter what I saw, I was going to treat the bronchitis. Even if the child had pneumonia on the x-ray, the treatment would be the same. When I saw the child later that week, he was just fine.
Everyone can do that - ask whether the x-ray would change the treatment. Sometimes the doctor orders one out of habit (like I did). Also be aware that some x-rays are highly unlikely to be helpful - for example, CAT scans of the head for headaches, x-rays for "charley-horse" back pain. The biggest contribution to the average person's lifetime dose of radioactivity is from health care professionals. We can all increase our awareness of the potential danger.
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