S80
Brachytherapy - Gynaecology
ESTRO 2026
Material/Methods: First fraction delineated MRI scans and treatment plans of 85 LACC patients previously treated with conventional intracavitary/interstitial BT applicators were acquired. The ARCHITECT applicator shape was based on the patient’s vaginal cavity and contained a standardized needle entry section. Optimal needle configurations were automatically determined using geometric coverage optimization with varying number of needles [1]. Automated treatment plans were generated with our in-house developed BiCycle software [2], following EMBRACE-II planning aims [3], for both conventional (TPConv) and three ARCHITECT configurations: TPARCH,A=highest geometric target coverage, TPARCH,B=highest geometric target coverage with same number of needles as conventional, and TPARCH,C=balancing geometric target coverage and organ-at-risk (OAR) distance. Without further fine-tuning, dosimetric parameters were extracted for all plans. Five radiation oncologists evaluated plan quality, clinical acceptability, and preference between TPConv and the optimal TPARCH configuration using 5-point Likert scales (1=strongly disagree to 5=strongly agree; 1=TPConv better to 5=TPARCH better) and MiM software (see Fig.1).
acceptability without fine-tuning achieved in 96% of the cases for TPARCH and 91% for TPConv. Fig. 2 presents an overview of preferences between TPConv and the optimal TPARCH configuration.
Conclusion: The ARCHITECT applicator enables improved needle selection and positioning, enhancing overall plan quality and adherence to planning aims. It offers a promising option for personalized BT in patients with challenging LACC presentations. Keywords: Cervical cancer, Applicators, 3D printing References: 1. Straathof, R., et al., Automated planning of curved needle channels in 3D printed patient-tailored applicators for cervical cancer brachytherapy. Physics in Medicine & Biology, 2024. 69(23): p. 235007.2. Rossi, L., et al., Prospective evaluation of AI-based BiCycle autoplanning for advanced cervical cancer brachytherapy. Radiotherapy and Oncology, 2025: p. 111029.3. Pötter, R., et al., The EMBRACE II study: The outcome and prospect of two decades of evolution within the GEC-ESTRO GYN working group and the EMBRACE studies. Clinical and translational radiation oncology, 2018. 9: p. 48-60. Comparison of Reference Point, Reference Line, and Inverse Optimization in 3-D Vaginal Cuff Brachytherapy Using an Ovoid Applicator Mehmet Varol 1 , Do ğ ukan Akçay 1 , Ece Özkaya 1 , Ece Ataç Kutlu 1 , Cenk Umay 1 , Bü ş ra Tozduman 2 , Emrullah Rıza Çetingöz 1 , Ay ş e Demiral 1,3 1 Department of Radiation Oncology, Dokuz Eylul University, Izmir, Turkey. 2 Department of Public Health, Dokuz Eylul University, Izmir, Turkey. 3 Department of Medical Physics, Dokuz Eylul University Institute of Health Sciences, Izmir, Turkey Digital Poster 4345
Results: All hard dose constraints were met, except for CTV- THR D90, which was achieved in 99% of TPARCH plans and 93% of TPConv plans. ARCHITECT plans more often met soft planning aims for CTV-THR D90/D98, CTV-TIR D98, and OAR D2cm3 compared to conventional plans (TPConv:81% versus TPARCH,A:90%, TPARCH,B:88%, and TPARCH,C:88%). The number of needles used was rated as significantly more appropriate for TPARCH (3.9±0.8) compared to TPConv (3.6±1.1), with significantly better geometrical positioning within the CTV (TPARCH:4.0±0.8; TPConv:3.3±1.1). Dwell time distribution was rated comparable (TPARCH:3.9±0.8; TPConv:3.8±0.8). Both TPARCH and TPConv plans received low scores for inappropriate hotspots (TPARCH:1.7±0.7; TPConv:1.9±0.8), indicating a minimal presence of problematic hotspots. Overall plan quality was rated significantly higher for TPARCH (4.1±0.6) compared to TPConv (3.6±0.8), with a clinical
Purpose/Objective: This study aimed to compare three different
optimization techniques-reference point optimization (RPO), reference line optimization (RLO), and inverse optimization (IO)-in terms of clinical target volume (CTV) and organs at risk (OAR) doses in gynecologic
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