Radiology now

At least 20 years ago it was suggested by the Russells (1952), and later the International Commission on Radiological Protection recommended (1966), that in women of child-bearing capacity non-urgent diagnostic radiography of the abdomen should be confined to the pre-ovulatory phase of the menstrual cycle, i.e., the ten days following the first day of the last menstrual period, on the assumption that ovulation occurs at about mid-cycle. Although the originators of the so-called "10-Day Rule" were mainly concerned to safeguard an embryo during the period of organogenesis, the principal hazard of low doses of X radiation is the increased incidence of childhood malignancies to which Dr. Alice Stewart first drew attention in 1956 (Stewart et al., 1968). It seems that each time a conceptus is exposed to whole-body irradiation of only a very few rads early in the course of a pregnancy, the risk of malignant disease developing in the child could be as much as trebled (Stewart and Kneale, 1968). In May, 1967 the Radiation Protection Committee of this Institute and the Royal College of Obstetricians and Gynaecologists organized a symposium on the effects of low radiation doses on the maturation of the developing (human) ovum and foetus (1968). Certain speakers on that occasion advocated the adoption of the "10-Day Rule".