ESTRO 2025 - Abstract Book

S279

Brachytherapy - Gynaecology

ESTRO 2025

References: 1. Gay HA, et al. Pelvic normal tissue contouring guidelines for radiation therapy: a Radiation Therapy Oncology Group consensus panel atlas doi:10.1016/j.ijrobp.2012.01.023 2. Salembier C et al. ESTRO ACROP consensus guideline on CT- and MRI-based target volume delineation for primary radiation therapy of localized prostate cancer. doi:10.1016/j.radonc.2018.01.014 3. Mir R, et al. Organ at risk delineation for radiation therapy clinical trials: Global Harmonization Group consensus guidelines. doi:10.1016/j.radonc.2020.05.038 4. Augurio A, et al. Contouring of emerging organs-at-risk (OARS) of the female pelvis and interobserver variability: A study by AIRO. doi:10.1016/j.ctro.2023.100688

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Mini-Oral Automating development of MDR-compliant patient-tailored 3D printed cervical cancer brachytherapy applicators Robin Straathof 1 , Sharline M. van Vliet-Pérez 2 , Linda S.G.L. Wauben 1 , Ben J.M. Heijmen 2 , Henrike Westerveld 2 , Inger Karine K. Kolkman-Deurloo 2 , Remi A. Nout 2 , Jenny Dankelman 1 , Nick J. van de Berg 3 1 BioMechanical Engineering, Delft University of Technology, Delft, Netherlands. 2 Radiotherapy, Erasmus MC Cancer Institute, University Medical Centre Rotterdam, Rotterdam, Netherlands. 3 Gynaecological Oncology, Erasmus MC Cancer Institute, University Medical Centre Rotterdam, Rotterdam, Netherlands Purpose/Objective: To improve target coverage in locally advanced cervical cancer brachytherapy (BT), 3D printed applicators guiding patient-specific interstitial needle configurations have been introduced. Development of these applicators has thus far required manual preplanning, which strongly relies on experience of the BT treatment team and is time consuming. In this work we present the design of the 3D printed ARCHITECT applicator, which is automatically generated by dedicated software and contains curved needle channels optimised for the individual target volume. We additionally highlight our framework for development under quality management systems (QMSs) as required per the Medical Device Regulation (MDR) 2017/745 in Europe. Material/Methods: The design of the ARCHITECT applicator and software followed a risk-based approach considering ISO 14971:2019. Design improvements were made based on safety and performance evaluations of: (1) intended benefits, including (1a) dose planning and (1b) patient experience; (2) usability, involving (2a) phantom insertion, (2b) mechanical evaluation, and (2c) patient geometry evaluations; (3) material properties, such as (3a) biocompatibility, (3b) dose attenuation, and (3c) sterilisation measurements; and (4) reproducibility, assessing (4a) needle insertion force, (4b) deflection, and (4c) applicator reconstruction. Iterations were documented in design history files and version control software. A manufacturer with QMS certification (ISO 13485:2016) was selected to 3D print the applicator. Software was manufactured in accordance with IEC 62304:2015. Technical documentation (Annex II, MDR) was compiled for initiation of a clinical study. Results: The final ARCHITECT applicator design is shown in Figure 1. To ensure comfort (as evaluated in study 1b), the applicator body consists of two halves, generated from concatenated MR vaginal cavity contours tapering to a circular entry region (2a & 2c). Connectors to the tandem are dimensioned to provide sufficient stiffness (2b). The needle channel configuration at the entry region is standardised to prevent mix-up. Sets of optimal needle channel configurations are automatically determined by the software, balancing needle count and dose conformity (1a). Easy and reproducible needle insertion and reconstruction is facilitated by minimising the curvature of the needle channels (4a), tapering of the channel ends (4b), and providing library reconstruction files (4c). The applicator is