Until recently, radium treatment of carcinoma of the cervix was prescribed in terms of milligram hours. Although such a designation is meaningless on radiobiological grounds, considerable experience has been acquired to guide treatments on a clinical basis. The amount and distribution of radium, both for the uterine tandem and the vaginal applicators, were empirically established by the pioneer Radium Centers. Through the years, cure rates improved and radiation damage decreased. Better results and less damage could still be obtained, however, by the same well developed technics, with a knowledge of the energy absorbed at the various points in the pelvis. The total amount and distribution of radium in the uterine tandem and vaginal applicators and the shape and design of the applicators might be changed to advantage. Without a knowledge of the radiation volume distribution, any change from a technic established on clinical experience is likely to become an almost entirely new technic, since a new applicat...