November 27, 1992

Medical X-ray

The radiologist doesn't sees the ultimate result of what he does; it happens 20 or more years later.

In 1895 Wilhelm Conrad Roentgen, a Professor of Physics in Germany, discovered that electrical discharges striking a metal target in a vacuum produced rays that would pass through flesh and make an image of bone on a platino-barium screen or a photographic plate. The first published x-ray picture was of his wife's hand. In 1901, he was awarded the Nobel Prize in physics.

Not long after Roentgen's discovery, it turned out that X-rays had serious side effects. Physicians had their fingers burned off and some developed cancer.

J.H. Muller proved that x-rays caused mutations, for which he received the Nobel Prize in Medicine in 1946. X-ray is now known to be one of the most powerful mutagens(causes mutation) and carcinogens(causes cancer) known. The justification for its continued use is that it is also a very powerful diagnostic and therapeutic tool. It is not possible to say how many people's lives have been saved by X-ray versus how many people have been killed by it.

There are a number of horror stories about the abuses of X-ray in medicine, ranging from a Buffalo N.Y. physician who would routinely shrink the thymuses of newborn infants with X-ray, to the treatment of a form of arthritis with it. The cases of cancer and leukemia caused by these treatments are well documented.

The number of cases of leukemia and other cancers produced by diagnostic X-rays is not so well documented, because of the difficulty of doing so. The only thing that we can be sure of is that in a country of 250 million people, it's a significant number and if every X-ray machine disappeared we would find an easily measurable drop in the cancer and leukemia rate. That would be balanced by lives lost for want of diagnostic and therapeutic x-ray.

When I had a tooth X-rayed at my dentist's office, his assistant put a lead apron and collar on me and then stepped behind a lead wall before taking the picture. The machine was a modern one, which means that it filters out those rays that don't help to get a picture of the tooth. The film is high speed and it takes less X-ray to get a good picture than with slower films, just as it takes less light to get a good picture with fast photographic film. I was surprised because, a scant 20 years ago, when I asked a dentist to protect my child, he ignored the request. This, despite the fact that scientists had been pleading with doctors and dentists for many years to protect their patients, particularly pregnant women, children and young adults. What it took to accomplish this miracle of protecting the patient, was for a whole generation of dentists to either retire or die.

Some 40 years ago, many premature infants developed a form of blindness called retrolental fibroplasia. When the discovery was published, that this blindness was related to the large amounts of oxygen given to premature infants, nurseries almost immediately reduced the amount of oxygen that they gave their "premies", and the condition promptly disappeared.

In contrast, after the deleterious effects of x-ray were proved, pleas by a number of scientists for the more judicious use of x-ray seemed to fall on deaf ears. Why the difference in attitude about the effects of high oxygen on newborns, and the mutations and cancer produced by radiation? Why were the findings immediately accepted in one case and as firmly rejected in the other?

I think that it has to do with the fact that the oxygen and the blindness could be immediately related, while the cancers and mutations caused by diagnostic X-ray could not. The doctor doesn't see the results of what he does; it happens 20 or more years later. Taking X-rays of a newborn child can cause leukemia, but the association is statistical. You can't say for sure that this particular child got that leukemia from this particular X-ray any more than you can say which particular cigarette caused a particular lung cancer.

Suppose that you had been doing something for your child for many years and you found out that what you had been doing was shortening his life, what would you do? Logic dictate that you would immediately stop doing what you were doing. A few people would stop doing it. But most people don't behave logically, and the response of the majority of people would be to deny that what they have been doing was harmful and to continue doing it. To admit that they have been harming their own children is so repugnant to most people, that the only way that they can deal with it is by denial.

Many members of the medical profession have difficulty with the concept of "risk." The practice of medicine does not deal with populations; it deals with individuals. If a physician knows that there is a risk of one in 10,000 of killing a patient with a treatment, and the treatment is effective, he will probably use it without worrying about it. If it is the only treatment, and the treatment is life-saving, he is correct to do so. The risks --and there are risks-- associated with most vaccines are very small compared to their life-saving potential. On the other hand, if that treatment will not be of great benefit to his patient, he should be aware that if 10,000 doctors each give that particular treatment to 100 patients, it will kill a total of 100 people. Even if a risk of one death in 10,000 is a small one, if there is no clear benefit attributable to the treatment, it should not be used. It is always necessary to weigh benefit against risk. Obviously, every doctor can't do that, so he is forced to accept the information provided by those who have checked it out. It is his business to be well informed.

A hellofalot of research has been done on the effects of ionizing radiation, radiation that can break molecules. Its effects have been measured in bacteria, plants, fruit flies, rats, mice and dogs. They have been roughly confirmed in people. With low dose radiation, such as is gotten from diagnostic X-rays, the mutagenic and carcinogenic effect is directly proportional(linear) to the dose. For example, if 30 rems of X-ray will produce 1 cancer death in 10 people, one rem will produce one cancer death in 300 people; one millirem ( a thousandth of a rem) will produce one death in 300,000 people.

We are exposed to between 80 and 200 millirems per year from natural sources. This background radiation is responsible for at least 80,000 cancer deaths per year in this country. There is absolutely nothing that we can do about it, short of moving to another planet. Doubling that amount of radiation, by adding diagnostic X-ray and environmental contamination with radioactive isotopes will double the number of radiation-induced cancers.

We know that there are cancers being caused by medical x-ray. What we don't know is how many. If every physician in the country cut the number of x-rays that he orders by half, it would also halve the number of x-ray produced cancers. This concept is usually greeted with blank stares by physicians because none have ever seen a case of cancer caused by medical x-ray. Actually, they have probably seen a number of them, but had no way of distinguishing them from cancers caused by other things.

X-ray is a very valuable tool and, when sensible precautions are taken to protect the patient, and unnecessary x-rays are avoided, the gain most probably outweighs the risk.

If you are the person whose life is saved by x-ray, the gain certainly outweighs the risk. If you are the person who gets cancer from x-ray, it doesn't.

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