Doses in critical organs as limits of the total dose in the treatment of women with inoperable endometrial carcinoma

Abstract

Surgery is the cornerstone of the treatments for endometrial carcinoma. However, about 20% of women must be treated with radiotherapy alone. They are patients in III FIGO stage and women in stage I and II with coexisting medical problems. The primary treatment of endometrial carcinoma is a combination of brachy-and teletherapy. During teletherapy the patients receive the total dose of 40–44 Gy to the treatment volume in pelvis with the use of the 4 beams-box technique. The second part of the treatment is intracavitary brachytherapy using two curved intrauterine applicators. The placing of the applicators in both corners of the uterus and individualized distribution of active sources in catheters make it possible to approximate the shape of isodoses to the size and shape of the uterus. On the basis of the AP and lateral radiographs with the parameters of the uterus we are able to plan the treatment according to the ICRU 38. The 50–55 Gy dose is distributed in two series with weekly intervals. We do not have much influence on the doses in the limiting organs (rectum, bladder) achived during teletherapy. Only the doses from brachytherapy can be modifed during treatment planning.

Doses in critical organs are limiting factors for the administred total dose from brachy and teletherapy. Using the Target 2 Plus system enables to obtain combined isodoses from two parts of the treatment. This approach makes it possible to determine the dose in the points in the limiting organs. The doses at points of maximum exposure, as well as the modification of that dose allow us to avoid the possible complications.