S78
Brachytherapy - Gynaecology
ESTRO 2026
Oncology, Catharina Hospital, Eindhoven, Netherlands. 4 Radiation Oncology, University Medical Center Utrecht, Utrecht, Netherlands. 5 Evolutionary Intelligence, Centrum Wiskunde & Informatica, Amsterdam, Netherlands Purpose/Objective: This study aimed to examine how cervical cancer brachytherapy (BT) treatment planning differs between Dutch centres, focusing on variations in planning aims and dose distributions. A multi-centre survey was conducted, complemented with a standardized planning task on one patient case, enabling comparisons between centres and validation
of the survey results. Material/Methods:
Two complementary analyses were performed.1. Questionnaire: A survey was distributed to all nine Dutch cervical brachytherapy centres, addressing clinical protocols for cervical cancer BT, including planning aims, evaluation of 3D dose distributions, and common catheter loadings.2. Planning benchmark: Until now, four centres received MRI data for one patient (cT2bN1M0) with reconstructed Geneva applicator and five interstitial needles, diagnostic MRI, and necessary patient information. They performed delineation and treatment planning following their routine clinical workflow for one BT fraction of 7 Gy, assuming a 4-fraction schedule. For visual analysis, a voxel-wise standard deviation (SD) heatmap was computed over all four plans to illustrate spatial variation in planned dose for a single fraction. Each plan was re-evaluated using every other centre’s delineation set, deriving inter-centre differences through median, minimum, maximum, and SD per planning aim – in total EQD2 values for 25x1.8Gy EBRT and 4x7Gy BT. For target volumes, the maximum pairwise volume difference was also determined. Results: Survey responses showed that all centres follow EMBRACE-II guidelines and share similar overall clinical philosophies (Table 1). Although planning preferences varied, metrics obtained for own plans on own delineations showed small inter-centre differences.
Conclusion: Findings suggest that applying a defined dose guidance for the vaginal mucosa can be achieved without compromising oncological adequacy, as HR- CTVD90 values remained within acceptable therapeutic limits. Further prospective clinical studies with larger patient cohorts are needed to evaluate the potential impact of reduced maximum point doses to the vaginal mucosa on treatment-related-AEs such as vaginal stenosis. Keywords: Endometrial cancer, mucosa-sparing References: Carrara, M., et al. (2017). "Comparison of different treatment planning optimization methods for vaginal HDR brachytherapy with multichannel applicators: A reduction of the high doses to the vaginal mucosa is possible." Physica Medica44: 58-65. A multi-centre comparison of cervical cancer brachytherapy treatment planning in the Netherlands Leah RM Dickhoff 1 , Ellen M Kerkhof 2 , Lavinia AL Verhagen 2 , Laura A Velema 2 , Paul MA van Haaren 3 , Petra S Kroon 4 , Karel A Hinnen 1 , Heloisa H Deuzeman 1 , Danique LJ Barten 1 , Lukas JA Stalpers 1 , Carien L Creutzberg 2 , Peter AN Bosman 5 , Bradley R Pieters 1 , Tanja Alderliesten 2 1 Radiation Oncology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands. 2 Radiation Oncology, Leiden University Medical Center, Leiden, Netherlands. 3 Radiation Proffered Paper 4008
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