(Potential) Mishaps of High-Dose-Rate Vaginal Cuff Brachytherapy

Abstract

Considering how commonly vaginal cuff brachytherapy is used, there is relatively little literature regarding the potential, albeit low, risk for complications. We present 3 potentially serious mishaps involving cylinder misplacement, dehiscence, and excessive normal tissue irradiation due to unique anatomy. Three patients with potentially serious treatment errors were encountered in the authors’ usual clinical practice. Each patient's records were reviewed for this report. For patient 1, computed tomography (CT) simulation revealed grossly inadequate cylinder insertion, which was most obvious on the sagittal view. For patient 2, CT simulation revealed that the cylinder extended beyond the perforated vaginal cuff and was surrounded by bowel. For patient 3, CT images were used only to verify cylinder depth. A standard library plan based on cylinder diameter and active length was used. In retrospect, the images revealed an unusually thin rectovaginal septum, with the lateral and posterior vaginal wall thickness estimated to be <2 mm. This patient's fractional normal tissue doses were calculated for this report, revealing a rectal maximum dose (per fraction) of 10.8 Gy, maximum dose that 2 cc of the organ receives of 7.4 Gy, and volume of the organ that receives the prescription dose or higher of 2.8 cc. All doses were far in excess of those anticipated for a minimal 0.5-cm vaginal wall depth. Vaginal cuff high-dose-rate brachytherapy is a high-volume, routine procedure. Even in experienced hands, however, it carries a risk of improper cylinder placement, cuff dehiscence, and excessive normal tissue dose, all of which could seriously affect outcomes. These potential mishaps would be better appreciated and avoided with more extensive use of CT-based quality assurance measures.