CRE calculations for different combined radiation therapy schemes of uterine cervical carcinoma.

The CRE concept is not applicable to the assessment of the effect of combined radiotherapy when external and intracavitary radiations are given alternately and with unequal doses. Because of the numerous recurrences, we had to change our radiation treatment schemes for carcinoma cervix uteri, and we attempted, on a theoretical basis, to acquire the same biological effects as Joslin with his own method. In the comparison of different schemes we used as slightly modified approximate CRE and the "nominal dose" presented by Kellerer. In this paper we have presented the treatment schemes we used and the methods for calculating the biological effect in combined treatments. Moreover, we have examined the applicability and compatibility of the above methods in comparing the effects of different combined radiation treatment schemes.