Applicator-dependent differences between TG-43 and a grid-based Boltzmann solver in iridium-192 high-dose-rate gynecological brachytherapy

Purpose

To compare TG-43 and Acuros® BV dose estimates in iridium-192 (192Ir) high-dose-rate (HDR) gynecological brachytherapy across four applicator types and evaluate applicator-dependent differences. The novelty was the systematic comparison of multiple applicators within a single-institution workflow. Material and methods: This retrospective dosimetric study included 40 patients and 121 treatment plans: tandem and ring (T&R, 34 plans), tandem and ovoid (T&O, 38 plans), segmented cylinder (SC, 23 plans), and universal multi-channel cylinder (UMC, 26 plans). All plans were generated in BrachyVision™ v. 15.6 using the TG-43 formalism and subsequently recalculated with Acuros® BV, with identical dwell positions and dwell times. The main analysis included high-risk clinical target volume (HR-CTV) D90, D98, and V100; organ-at-risk (OAR) D2cc; Point A for T&R/T&O; and the SC 100% prescription-isodose position at 5 mm depth. Exploratory dwell-loading descriptors and a density-cap quality assurance audit supported physical and methodological interpretation.