S1738
Physics - Dose prediction/calculation, optimisation and applications for particle therapy planning
ESTRO 2026
Digital Poster 2643 Comparison of a dedicated vs a general-purpose system for single metastases intra-cranial stereotactic fractionated radiotherapy Daniel Lambisto Castro 1 , Ignasi Modolell i Farré 1 , Diego Jurado-Bruggeman 2 , Carles Muñoz-Montplet 2 1 Medical Physics and Radiological Protection, ICO- Duran i Reynals, Hospitalet de Llobregat, Spain. 2 Medical Physics and Radiological Protection, ICO- Girona, Girona, Spain Purpose/Objective: To compare the performance of a dedicated versus a general-purpose system for single-lesion intracranial stereotactic fractionated radiotherapy. Material/Methods: In a multicentric institution, two approaches are followed depending on the center to treat intra-cranial peripheral lesions. One center (Center A) uses a dedicated system combining BrainLab Elements with a TrueBeam Novalis featuring a 120HD MLC, delivering plans with four non-coplanar arcs aimed at achieving 99.5% of the PTV receiving the prescribed dose. The other center (Center-B) employs a general-purpose system with Eclipse planning for a TrueBeam equipped with a 120 Millennium MLC, using five pre- defined non-coplanar arcs to achieve a homogeneous dose distribution (VPTV95% > 98% and VPTV110% < 5% of the prescribed dose). Seven patients with single metastases treated at the second center were randomly selected and replanned using the first center’s workflow. The prescription dose was 35 Gy in five fractions. For both techniques, dosimetric parameters were compared: average, maximum, and minimum PTV doses; conformity and gradient indices (CIPaddick, GIPaddick, and CILomax); and RTOG indices for homogeneity (HIRTOG), quality of coverage (QRTOG), and conformity (CIRTOG) [1,2]. Regarding organs-at-risk (OAR), derived metrics included V24Gy for the brain, V26Gy for the brainstem, mean dose (Dmean) for the cochleas, and maximum doses (Dmax) for the eyes, optic chiasm, and optic nerves. Comparisons were performed using boxplots and Wilcoxon tests ( α = 0.05).
Figure 2 Dose metrics and differences for single-field and multi-field plans evaluated by 4DDD based on r4DCT(a) and c4DCT(b). Each plan was normalized to cover 95% of the ICTV with 100% of the prescribed dose, with reference lines for D95% and V25. Conclusion: Respiratory motion contributes more significantly to proton dose uncertainty than cardiac pulsation in VT treatment. Multi-field plans with main angles of 60°, 60°, 90°, and 30° for the anterior, inferior, lateral, and septal targets, respectively, offer optimal balance between target coverage and normal tissue protection. Patient-specific 4D robust evaluation is essential to ensure treatment safety and precision. References: 1. Cuculich, P.S., et al. Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia. N Engl J Med. 2017; 377(24): p. 2325-2336.2. Widesott, L., et al. Proton or photon radiosurgery for cardiac ablation of ventricular tachycardia? Breath and ECG gated robust optimization. Phys Med. 2020; 78: p. 15-31.3. Milo, M.L.H., et al. Delineation of whole heart and substructures in thoracic radiation therapy: National guidelines and contouring atlas by the Danish Multidisciplinary Cancer Groups. Radiother Oncol. 2020; 150: p. 121-127.4. Wei, W., et al. Quantifying dose uncertainties resulting from cardiorespiratory motion in intensity-modulated proton therapy for cardiac stereotactic body radiotherapy. Front Oncol. 2024; 14: p. 1399589. Keywords: Ventricular tachycardia,4D dynamic dose
Made with FlippingBook - Share PDF online