Effect of bladder distension on dosimetry in gynecological implants

In order to quantitate the impact of bladder distension on implant position and on radiation dosage to various parts of the bladder, 24 patients with gynecological neoplasms underwent computed tomographic scanning of the pelvis following insertion of afterloading intracavitary applicators. Shifting of the applicators due to bladder distension was measured at and two inches above the level of the vaginal ovoids. By maintaining a residual vesical volume of 200-300 ml with contrast material, radiation exposure to a large part of the bladder was reduced significantly while only a minor displacement of the implant system was noted.