S2792
RTT - RTT contouring, target definition, and treatment planning
ESTRO 2026
were developed to streamline plan generation and reduce planning time, making VMAT planning feasible within the same timeframe as static field techniques. VMAT plans were compared with two static plans: one posterior field and two oblique fields. Results: The three plans for one patient are shown in Figure 1. The field directions and arc segments used are also indicated in the figure.Target coverage: The VMAT plan provided a more homogeneous dose to the PTV. The oblique static fields covered the target, but showed poor conformity, while the single posterior field failed to adequately cover the ventral part of PTV.OARs: The kidneys received no dose either with VMAT or the posterior plan, while the oblique fields irradiated the kidneys. A larger intestinal volume was irradiated with both static plans compared with the VMAT plan. Figure 1. Dose distribution comparison between one static posterior field (left), two oblique posterior fields (middle) and VMAT (right) for a vertebral metastasis. Dose cutoff is 20% (5 Gy). The PTV is defined in turquoise. Conclusion: The described VMAT technique improved target coverage and reduced OAR doses compared with static posterior fields. By implementing plan templates and FFF beams, planning and delivery times were minimized. This approach offers a practical and efficient solution for palliative vertebral irradiation while reducing the risk of acute side effects. References: Tsuzuki et. al: Skeletal complications in cancer patients with bone metastases, International Journal of Urology (2016) 23, 825-832 Keywords: VMAT, dose distribution, vertebrae Fast collision detection integrated in treatment planning system improved using surface scans from CT simulation Alicia Palmér 1 , Joachim Marichal 2,3 , Ola Weistrand 1 , Mattias Nilsing 4 1 Research, RaySearch Laboratories, Stockholm, Sweden. 2 Department of Radiation Oncology, Iridium Network, Antwerp, Belgium. 3 Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium. 4 Research and development, C-RAD Positioning AB, Uppsala, Sweden Digital Poster 3581
control probability and thus improve the quality of life. References: 1.Zobec Logar H.B., Hudej R., Š egedin B. Development and assessment of 3D-printed individual applicators in gynecological MRI-guided brachytherapy. Journal of Contemporary Brachytherapy. 2019;11(2):128- 136.2.Segedin B., Kobav M., Zobec Logar H.B. The Use of 3D Printing Technology in Gynaecological Brachytherapy—A Narrative Review. Cancers. 2023;15(16):4165.3.Pötter R, Georg P, Dimopoulos JC et al. (2011). Clinical outcome of protocol based image (MRI) guided adaptive brachytherapy combined with 3D conformal radiotherapy with or without chemotherapy in patients with locally advanced cervical cancer. Radiother Oncol 100(1): 116-23. Keywords: brachytherapy, 3-D print applicator, custom-made Digital Poster 3424 Benefits in dose distribution using VMAT technique for palliative vertebral treatments Maria Medin 1 , Frida Dohlmar 2,3 , Emelie Adolfsson 3 1 Clinical Department of Oncology in Linköping, Region Östergötland, Linköping, Sweden. 2 Department of Health, Medicine, and Caring Sciences, Linköping University, Linköping, Sweden. 3 Clinical Department of Medical Radiation Physics, Region Östergötland, Linköping, Sweden Purpose/Objective: Vertebral metastases are common in many cancer patients and can lead to complications such as pain, pathological fractures, and spinal cord compression1. Because several organs at risk (OARs), including the spinal cord, kidneys, esophagus, lungs, heart, and intestines, are located close to the target, treatment may result in significant side effects. Advanced delivery techniques such as VMAT can improve dose conformity and spare OARs. The purpose of this work was to describe a VMAT technique for the treatment of vertebral metastases, aiming to achieve optimal target coverage while minimizing dose to OARs. Material/Methods: All patients receiving palliative radiotherapy for vertebral metastases underwent planning CT scans, and both target volumes and OARs were delineated. Treatment planning was performed in Eclipse TPS (Varian Medical Systems, Palo Alto, USA). VMAT plans were generated using four posterior arc segments. Arc length was adapted to target location: typically 120°– 240° for cervical or thoracic lesions and up to 90°–270° for sacral lesions. Flattening filter-free (6 FFF) beams were preferred to reduce delivery time, except for long targets where 6 MV was used. Planning templates
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