Computed tomography measurements of the cervix and distances to the bladder and rectum in intracavitary radiation treatment of gynaecological cancer.

Improved knowledge of the topography of target and adjacent organs in intracavitary irradiation of gynaecological tumours is needed when a high dose rate afterloading system with good precision is used. To get this information, 16 patients with small carcinomas were examined by computed tomography scan with applicators inserted. The thickness of the vesico and rectovaginal septa was measured. In the ten cervical carcinomas the minimum thickness was 4 mm. In the six early corpus carcinomas the vesicovaginal septum thickness was 7 to 9 mm while the rectovaginal septum thickness was 5 to 7 mm. Measurement of the cervical diameter seems to be valuable and can give information about suitable intracavitary target dimensions. In this way overtreatment of the bladder and rectum can be avoided and a more precise dose can be delivered to the entire target volume.