ESTRO 2024 - Abstract Book

S218

Brachytherapy - Gynaecology

ESTRO 2024

Magnetic resonance-guided brachytherapy (MRgBT) is the gold-standard treatment for cervical cancer. However, MRgBT is resource intensive and requires coordination in the operating room, MR-imaging, planning and treatment delivery. An integrated MRgBT suite that enables all activities to be performed with the patient under general anesthesia can maximize efficiency, reduce patient discomfort and facilitate optimal needle placement with intraoperative MR-guidance. This study examined workflow times for combined intracavitary/interstitial cervix brachytherapy and factors contributing to intraoperative efficiency in an integrated MRgBT suite.

Material/Methods:

Consecutive patients with FIGO stage IB-IVA cervical cancer who underwent MRgBT procedures (28 Gy/4F or 24 Gy/3F) in an integrated MRgBT suite as part of definitive treatment between 2019-2022 at an academic center were retrospectively reviewed. For patients who underwent one or more of their brachytherapy procedures in a conventional operating room, only the procedure times in the integrated MRgBT suite are included in this study. The following key workflow times for intraoperative MRgBT were collected: room entry; applicator insertion; room transition (converting room to MR-safe environment and moving MR scanner on rail into the procedure suite); MR-simulation (including intraoperative needle adjustment based on MR images); contouring; treatment planning; treatment delivery; total procedure time (from room entry to end of brachytherapy treatment delivery); transportation from MRgBT suite to the post anesthesia care unit (PACU); and recovery from anesthesia in PACU. High-risk clinical target volume (CTV HR ), number of needles inserted, and duration of procedures were compared between applicator types using linear regression with generalized estimating equations (GEE) to account for intra patient correlation. To assess change in duration of brachytherapy procedure over time, a multivariable linear regression model with GEE was fitted, adjusting for potential confounders including applicator type and CTV HR . The 161 patients included in this study underwent a total of 267 procedures in the integrated MRgBT suite. Median age was 50 (range 25-88). The majority were T2b (52%), and FIGO stage IIB (20%) or IIIC1 (40%). Median tumor size at diagnosis was 4.6 (0.4 - 10.6) cm; median CTV HR was 27.6 (10.9-136.8) cm 3 ; and median CTV HR D 90% was 91.2 (85.1-98.6) Gy 10 . The majority of procedures used interstitial needles (99%), with the Venezia applicator (46%), followed by ring and tandem (R&T, 28%) and Syed-Neblett template (27%). Cases treated with the Syed-Neblett template had larger CTV HR and greater number of needles inserted compared to R&T and Venezia (p < 0.001, Table 1). Procedures using the Syed-Neblett template were associated with longer insertion (by 9 minutes, p < 0.001), MR-simulation (by 14 minutes, p < 0.001), contouring (by 9 minutes, p < 0.001), planning (by 26 minutes, p < 0.001), total procedure time (by 52 minutes, p < 0.001) and recovery time (by 14 minutes, p < 0.001) compared with those using the R&T or Venezia applicators. Total procedure time for Syed-Neblett cases reduced by 10 minutes per year since 2019 (p < 0.001). Regardless of applicator type, total procedure time for subsequent insertions were 21 minutes less than the first (mean 199 ± 39 minutes vs 220 ± 44 minutes, p < 0.001). Results: