The dosimetric impact of vaginal balloon-packing on intracavitary high-dose-rate brachytherapy for gynecological cancer

Abstract

PurposeWe perform a clinical retrospective study to determine whether a vaginal balloon-packing system provides a dosimetric reduction to organs at risk (OARs) versus traditional gauze packing for gynecological high-dose-rate brachytherapy (HDR-BT). We also test various balloon filling materials for optimizing imaging quality.Material and methodsFilling materials for balloon-packing were evaluated based on imaging quality with X-ray, computerized tomography, and magnetic resonance imaging modalities. We then retrospectively reviewed 45 HDR-BT plans of 18 patients performed with gauze packing and 39 plans of 16 patients performed with balloon-packing. Twelve patients received both gauze and balloon-packing. HDR-BT was delivered with an iridium-192 afterloader and a Fletcher-Suit-Declos-style T&O applicator. At each fraction, 3D imaging was obtained. The D2cc values of OARs were calculated, as well as ICRU-defined point doses.ResultsIn the 84 HDR fractions reviewed, vaginal balloon-packing provides statistically equivalent doses to rectum, bladder, and sigmoid compared to gauze packing. On average balloon-packing produced average reductions of 3.3% and 6.9% in the rectal and sigmoid D2cc doses and an increase of 3.2% to the bladder D2cc dose (normalized to prescription dose), although none of these values were statistically significant for the twelve patients who received both gauze and balloon-packing (32 and 40 total fractions, respectively).ConclusionsIn the 84 HDR fractions analyzed, vaginal balloon-packing is as effective as gauze packing for dose sparing to the rectum, bladder, and sigmoid. A 1: 1 solution of saline and contrast for filling material enables easy contouring for image-guided HDR with minimal artefacts.

Bladder–Rectum Spacer Balloon versus Vaginal Gauze Packing in High Dose Rate Brachytherapy in Cervical Cancer: A Randomised Study (Part II)

“…However, a significant proportion of the bladder dose originates from its proximity to the anteverted uterus, as well as the shape that wraps around the uterus [5,10]. Moreover, the angle of the uterine tandem may significantly influence the doses to the bladder, although in the present study, its impact could not be evaluated as the same applicator was used for both applications.…”

“…This could be attributed to the relatively small sample size in our study. In a retrospective study by Rockey et al [5], 45 HDR plans of 18 patients with gauze packing were compared with 39 plans of 16 patients with balloon packing. Although the balloon resulted in a statistically non-significant reduction in doses to the rectum and sigmoid, slight increases in doses to the bladder were observed with the balloon.…”

“…Traditionally, vaginal packing with gauze has been used for displacing the bladder and rectum away from the vaginal sources. This simple and costeffective procedure helps to reduce doses to these OARs and facilitates in stabilising the applicator position [5]. Although vaginal gauze packing (VGP) is a reliable method to push the bladder and rectum away from the applicators, it lacks reproducibility and is dependent on the physician's expertise for proper placement.…”

Brachytherapy in pelvic malignancies: a review for radiologists

“…Gauze impregnated with ultrasound gel has been shown to provide the greatest degree of MRI contrast with respect to the applicator and cervix [30]. Potential pitfalls include loose packing or an uneven distribution of gauze [29].…”

“…Surgical packing is placed within the vagina to displace the bladder, rectum, urethra, and vaginal walls, as well as to limit device movement; povidone-iodine-impregnated gauze can help visualize the packing if intraoperative radiography is performed to evaluate the implant. The quality of gauze packing is dependent on the experience and skill of the radiation oncologist performing the procedure [29]. Gauze impregnated with ultrasound gel has been shown to provide the greatest degree of MRI contrast with respect to the applicator and cervix [30].…”