S2771
RTT - RTT contouring, target definition, and treatment planning
ESTRO 2026
1 Department of Radiation Oncology, National University Cancer Institute of Singapore, Singapore, Singapore. 2 Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Australia
Digital Poster 1430
Lateral/anterior oblique beams may enhance dosimetric outcomes over conventional AP\PA beams in SCV irradiation in breast cancer irradiation. Nagwan Ibrahim Anter 1 , Medhat Mohamed Ei Sebaie 1 , Sabreen Abdo Mohammed 1 , Karim Elsayed Eldakak 2 1 radiotherapy, National cancer institute, cairo, Egypt. 2 radiotherapy, Gharbia cancer society, Tanta, Egypt Purpose/Objective: This study evaluates the dosimetric performance of two radiotherapy field arrangements—anterior–lateral (AP/Lat) and conventional anterior–posterior (AP/PA)— for supraclavicular (SCV) nodal irradiation in breast cancer patients. SCV irradiation is a critical component of adjuvant radiotherapy, but its proximity to vital organs such as the lung, thyroid, and humeral head necessitates careful planning to ensure effective tumor coverage while minimizing exposure to organs at risk (OARs). The conventional AP/PA technique, while widely used, may result in excessive dose to posterior tissues, including the back skin and latissimus dorsi, which is particularly concerning for patients undergoing reconstructive surgery Material/Methods: The study retrospectively replanned SCV irradiation for 30 breast cancer patients using both AP/Lat and AP/PA techniques on identical CT datasets. Each plan prescribed 40 Gy in 15 fractions, normalized to deliver at least 95% of the dose to 95% of the planning target
Conclusion: PBT demonstrates resilience to inter-fractional organ motion in cervical cancer treatment. Existing bladder and bowel preparation protocols appear sufficient for clinical PBT implementation in cervical cancer. Rectal filling is known to increase rectal dose due to its proximity to the target, highlighting the need for interventions such as bowel preparation. Further prospective studies with larger cohorts are warranted to confirm these findings and inform adaptive strategies. References: 1) Ballari, N., Rai, B., Bahl, A., Mittal, B. R., & Ghoshal, S. (2021). Prospective observational study evaluating acute and delayed treatment related toxicities of prophylactic extended field volumetric modulated arc therapy with concurrent cisplatin in cervical cancer patients with pelvic lymph node metastasis. Technical innovations & patient support in radiation oncology, 17, 48–56. https://doi.org/10.1016/j.tipsro.2021.02.009 Keywords: Proton Beam Therapy, Cervical Cancer, Organ Motion
Digital Poster 1390 Functional Imaging for Organ-at-Risk Sparing in
Patients with Glioma Li Wen Yeo 1 , John Ryan 2
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