Patients are getting worried about X rays. Following the National Academy of Sciences' Report to the Public on the biological effects of radiation (TIME, June 25), more and more people have begun to nag doctors and dentists about possible harmful effects. Many have flatly refused to submit to X-ray examination or treatment. Just how safeor dangerousare X rays?
Too much radiation at one body site can cause skin conditions resembling severe burns or local cancers. Widely distributed over the body so that it penetrates much of the blood-forming marrow, excessive radiation can cause leukemia. If it strikes the gonads (ovaries or testicles), excessive radiationi.e., by best estimate, beyond 10 roentgens*can cause mutations in the genes, which, in turn, may mean deformities in the patient's descendants. Dangers, by sites:
Dental. The average dental X ray now delivers 5 r., but this is only to the jaw: the "scatter" radiation reaching the gonads from this is a mere .005 r. in a man and .001 r. in a woman. It would thus take 2,000 X rays to deliver a presumably damaging 10 r. to a man's gonads. Even so, notes the Journal of the American Dental Association, the currently used 5-r. doses are unnecessary. In the same issue, Radiologist Lewis E. Etter of Pittsburgh tells dentists how (by using higher voltages, better filters, faster films, shorter exposures) they can cut down the total radiation used in each exposure to a piddling .1 r. The National Bureau of Standards has developed another way to reduce X-ray exposures: a panoramic machine (see cut) which photographs the entire mouth with a single, sharply focused exposure instead of 14 separate plates.
Chest. The conventional shot at a 6-ft. range on a film 14 by 17 in. delivers .06 to .1 r. to the chest, about .001 r. to the gonads. At the 24-in. ranges used in mass chest surveys, the dosages go as high as 2 r. to the chest, but the scatter to the gonads is scarcely increased. But fluoroscopy, in which the image is viewed instantaneously on a screen, takes longer, may entail 3 to 10 r. per minute to the chest and .1 to .4 r. per minute to the gonads.
Prenatal. X rays of pregnant women may endanger the fetus. Oxford University researchers report that among the mothers of British children who had died of leukemia X rays of the pelvis during pregnancy (necessarily exposing the entire fetus to radiation) had been twice as common as among the mothers of other children. This was no conclusive finding, but a warning flag against haphazard X rays of the pregnant.
Arms & Legs. X rays of limbs to detect possible fractures, or arthritic deposits in joints, usually require only short exposures. The radiation used is not enough to damage bone marrow, is far enough from the gonads for safety.
Therapeutic. Although the amounts of radiation required in medical treatment, e.g., for cancer, average much higher than those in diagnosis, they are generally safer. Treatment usually is given by a radiologist who uses elaborate shielding to protect parts of the body not intended to be irradiated. In some cases, radiologists take a calculated risk of damaging some healthy tissues for the sake of attacking the cancer and prolonging life.