AbstractsIn 1970, the International Commission on Radiological Protection established guidelines for the protection of pregnant patients and workers from overexposure to radiation. One of the major proposals has come to be known as “the 10-day rule.” The Commission recommended that physicians confine less urgent radiological examinations to the 10 days following the start of menstruation, this being the time when pregnancy is least probable.The 10-day rule was modified in 1984 to extend the period of relative safety. The Commission issued the following statement: “During the first 10 days following the onset of a menstrual period, there can be no risk to any conceptus since no conception will have occurred. The risk to a child who has been irradiated in utero during the remainder of a 4-week period after the onset of menstruation is likely to be so small that there need be no special limitation on exposure during these 4 weeks.”The National Radiological Protection Board in the United Kingdom issued new guidelines in 1985, conforming to those of the International Commission. The following comments appeared in two British medical journals.“The risk to the fetus from diagnostic radiological examinations seems to be insignificant. The cost of implementing the 10-day rule would be some 100 times greater than the possible benefit derived from it, assuming that a benefit exists.”“When a patient is regarded as pregnant, special care should be taken to ascertain whether the radiological procedure is necessary. Since the risk of irradiating the fetus may be much less than that of failing to make a correct diagnosis, the procedure should be carried out if a need is indicated, but with particular care to minimize the radiation dose to the fetus.”The U. S. Food and Drug Administration endorsed the new guidelines in 1985, recommending also that patients be cautioned against breast-feeding after nuclear irradiation. The FDA also suggested that patients be advised to postpone planned pregnancies after radkxiuclide procedures for a length of time specified by a nuclear medicine physician.Concern about the risk of radiation exposure to pregnant workers has received increasing attention. According to the American Association of Women Radiologists, the evidence is reassuring. There are misconceptions about the actual amounts of radiation that reach the conceptus during occupational exposure. The doses involved are often less than those from environmental sources. The spread of this information should help to alleviate the emotional trauma and guilt suffered by all radiation workers with affected children. It is suggested that each hospital establish a realistic policy that will allow pregnant workers to protect their jobs, safeguard their unborn children, and fulfill their professional obligations.