Simplified irradiation dosimetry in carcinoma of the cervix (external irradiation and one radium insertion).

Gynecologic radiation oncologists have long desired a single unit by which radiation doses to specific reference points in the pelvis can be summed. The Patterns of Care Studies, Marcial's 1976 report to the Conference on Radiation Oncology of the American Cancer Society, and other radiation oncologists advise summed doses to Point A, Point B, or the pelvic side wall. Since there is a difference in the biologic effect of high intensity, long time interval teletherapy and low intensity, short time interval brachytherapy, the rad dose obtained from each modality cannot be simply added. Ellis and Sorenson in the Nominal Standard Dose (NSD) concept have described radium conversion factors that can be used to normalize brachytherapy rads at selected reference points to equivalent teletherapy rad. The two rad doses can then be summed. A simple method found useful in 50 cases of carcinoma of the cervix, and used with a computer or readily available reference tables and with any radium system, is described and discussed. Further clinical uses of the method are suggested.