S1979
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
heterogeneity for both techniques. However, in all evaluated cases, actual anatomical deformation was minimal compared to the theoretical extent of the fall- off region. This may explain why the differences between techniques were relatively small in these scenarios. References: [1] Munshi A et al. doi:10.1007/s13246-017-0558-y[2] Fogliata A et al. doi:10.1186/s13014-015-0392-x[3] Nicolini G et al. doi:10.1118/1.3598442[4] Boman E et al. doi:10.1016/j.ejmp.2016.10.012[5] Lizondo M et al. doi:10.1016/j.ejmp.2019.05.010[6] Coles CE et al. doi:10.3310/eme01030 Keywords: Breast, VMAT, AFM New tool in treatment plan system to improve clinical decision: Multi-criteria Optimization DAVID HERNANDEZ 1,2 , JAVIER SANCHEZ 1 , MAITE QUINTANA 1 , JUAN ALTAYO 1 , PATRICIA DONCEL 1 , NAGORE FERNÁNDEZ 1 , TANIA HERNANDEZ 1 1 MEDICAL PHYSICS, COMPLEJO ASISTENCIAL UNIVERSITARIO DE SALAMANCA/ HOSPITAL NUESTRA SEÑORA DE SONSOLES, AVILA,, Spain. 2 MEDICAL PHYSICS, INSTITUTE OF BIOMEDICAL RESEARCH OF SALAMANCA, SALAMANCA, Spain Purpose/Objective: The development of new system tools improves the quality and safety of patient treatments.This study aims to analyse the improvements that the use of the multi-criteria optimization tool (MCO) can bring to VMAT treatments planning. Material/Methods: 15 patients with rectum carcinoma were analysed. The treatment planning system (TPS) used was Eclipse V.16.1 and the calculation algorithm was Acuros1612 Digital Poster 4134 (Varian)All plans were calculated with the same objectives and priorities, with and without MCO. All patients were prescribed a dose of 50Gy in the planning target volume (PTV) with 95% coverage. The mean dose (Dmean) and maximum dose (Dmax) of PTV have also been analysed. The organ risk limits analysed were bladder (Dmean, V45Gy and V40Gy) and bowel (Dmean and D65cm3). Results: Image1 shows that 95% PTV coverage are very similar between with and without MCO planning. Mean and maximum doses in PTV are slightly higher in plans without MCO, but less than 1%.
and replanning criteria were evaluated through plan recalculations based on CBCT derived anatomical
changes. Results:
The following figures and tables illustrate coverage and dose homogeneity in the fall-off region for both approaches. They also include recalculations of the original plans, incorporating breast changes observed in CBCT imaging:
Conclusion: For breast cancer cases requiring supraclavicular node irradiation, incorporating a shoulder avoidance structure in VMAT planning effectively reduces dose to
the shoulder region without increasing plan complexity.The pseudo-skin flash technique
combining a virtual bolus with AFM demonstrated superior coverage and dose homogeneity in the fall- off region compared to AFM alone.Replanning criteria based on IGRT showed acceptable coverage and
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