Clinical analysis of speculum-based vaginal packing for high-dose-rate intracavitary tandem and ovoid brachytherapy in cervical cancer

Abstract

PurposeIntra-vaginal packing is used to fix the applicator and displace organs at risk (OAR) during high-dose-rate intracavitary tandem and ovoid brachytherapy (HDR-ICB). We retain the speculum from applicator placement as a dual-function bladder and rectum retractor during treatment. Our objective is to review salient techniques for OAR displacement, share our packing technique, and determine the reduction in dose to OAR and inter-fraction variability of dose to OAR, associated with speculum-based vaginal packing (SBVP) in comparison to conventional gauze packing during HDR-ICB.Material and methodsWe reviewed HDR-ICB treatment plans for 45 patients, including 10 who underwent both conventional gauze packing and SBVP. Due to institutional inter-provider practice differences, patients non-selectively received either packing procedure. Packing was performed under conscious sedation, followed by cone beam computed tomography used for dosimetric planning. Maximum absolute and percent-of-prescription dose to the International Commission of Radiation Units bladder and rectal points in addition to D0.1cc, D1.0cc, and D2.0cc volumes of the bladder and rectum were analyzed and compared for each packing method using an independent sample t-test.ResultsOf the 179 fractions included, 73% and 27% used SBVP and gauze packing, respectively. For patients prescribed 6 Gy to point A, SBVP was associated with reduced mean D0.1cc bladder dose, inter-fraction variability in D0.1cc bladder dose by 9.3% (p = 0.026) and 9.0%, respectively, and statistically equivalent rectal D0.1cc, D1.0cc, and D2.0cc. Patients prescribed 5.5 Gy or 5 Gy to point A after dose optimization, were less likely to benefit from SBVP. In the intra-patient comparison, 80% of patients had reduction in at least one rectum or bladder parameter.ConclusionsIn patients with conducive anatomy, SBVP is a cost-efficient packing method that is associated with improved bladder sparing and comparable rectal sparing relative to gauze packing during HDR-ICB without general anesthesia.

A comparison of dosimetric parameters in high-dose-rate intracavitary brachytherapy using tandem and ring applicators: is the combination of a rectal retractor and radio-opaque vaginal packing better than rectal retractor alone for rectum sparing in cervical cancer?

“…It is pertinent to discuss similar packing methods used in place of conventional VP to displace OARs with T&O applicators [24][25][26][27][28]. Rockey et al [24] showed that the commercially available vaginal balloon packing system provides statistically equivalent OAR protection compared to traditional VP in HDR-BT performed using T&O applicators.…”

Reproducibility of vaginal immobilization balloons in situ overnight for cervical cancer brachytherapy

“…There are numerous ways to displace OARs during brachytherapy procedures, including traditional gauze packing, balloons, and retractor blades [12]. Evaluating the overnight variability of these devices is important for do- simetric reasons and disease control, as Viswanathan et al [21] showing that variability in brachytherapy placement may decrease disease control.…”

“…To limit the RT exposure to organs at risk (OARs), the current practice is to insert lubricated strips of gauze or other packing material into the space between the applicator and the anterior and posterior vaginal walls. This fixes the applicator and displaces the bladder and rectum anteriorly and posteriorly, respectively, thus reducing the overall dose delivered to these organs [12].…”

Dosimetric effects of the Smit sleeve on high-dose-rate brachytherapy tandem and ovoids plans for patients with locally advanced cervical cancer

“…Practitioners should be cognizant of these effects and evaluate the patient's anatomy prior to brachytherapy to determine whether distal displacement of the ovoids through the use of a Smit sleeve could impact the dose delivered to the OARs. In addition, they should consider using other techniques to reduce the dose to OARs such as speculum based vaginal packing [12], changes to bladder volume [13] or other techniques.…”