The British Journal of Radiology, Vol 52, Issue 618 468-471, Copyright © 1979 by British Institute of Radiology

ARTICLES

The effect on dosimetry of changing from the lithotomy to the supine position in treating uterine cancer with the Cathetron and external radiotherapy

M Bjornsson and B Frankendal

Uterine carcinoma can be treated by combined external and intracavitary irradiation. With an afterloading technique intracavitary irradiation is given with the patients in the lithotomy position. External irradiation is given with the patient in the supine position. A lead shield is used with the external fields to cover the tissues which are close to the intracavitary sources and receive high doses. The positions of the intracavitary sources seen on radiographs taken when the patient is in the lithotomy position are transferred to films taken with the patient in the supine position. From the latter the position and profile of the shield are calculated. It is shown that a reliable transfer of the positions of the sources and determination of the necessary shielding cannot be achieved in this way. It is therefore concluded that both intracavitary and external irradiation should be carried out with the patient in the supine position.