ESTRO 2024 - Abstract Book

S2063

Clinical - Paediatric

ESTRO 2024

References:

1. van den Bent M, Wefel J, Schiff D, Taphoorn M, Jaeckle K, Junck L, et al. Response assessment in neuro-oncology (a report of the RANO group): assessment of outcome in trials of diffuse low-grade gliomas. Lancet Oncol. 2011 Jun;12(6):583–93.

2. Indelicato DJ, Rotondo RL, Uezono H, Sandler ES, Aldana PR, Ranalli NJ, et al. Outcomes Following Proton Therapy for Pediatric Low-Grade Glioma. Int J Radiat Oncol Biol Phys. 2019 May 1;104(1):149–56.

3. Wen PY, van den Bent M, Youssef G, Cloughesy TF, Ellingson BM, Weller M, et al. RANO 2.0: Update to the Response Assessment in Neuro-Oncology Criteria for High- and Low-Grade Gliomas in Adults. J Clin Oncol. 2023 Sep 29;JCO2301059. 4. Stock A, Hancken CV, Kandels D, Kortmann RD, Dietzsch S, Timmermann B, et al. Pseudoprogression Is Frequent After Front-Line Radiation Therapy in Pediatric Low-Grade Glioma: Results From the German Low-Grade Glioma Cohort. Int J Radiat Oncol Biol Phys. 2022;112(5):1190-1202.

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Digital Poster

Total Body Irradiation: moving from 2D to 3D VMAT: a single experience

Elisa Meldolesi 1 , Silvia Chiesa 1 , Silvia Mariani 1 , Francesca Greco 2 , Francesco Beghella 1 , Elisa Marconi 3 , Stefania Manfrida 1 , Vincenzo Frascino 1 , Nicola Dinapoli 1 , Luca Indovina 2 , Giulia Panza 1 , Francesco Pastore 1 , Silvia Longo 1 , Maria Antonietta Gambacorta 1 1 Policlinico Gemelli IRCCS, Radiation Oncology, Rome, Italy. 2 Policlinico Gemelli IRCCS, Fisica per le scienze della vita, Rome, Italy. 3 Policlinico Gemelli IRCCS, Psicology, Rome, Italy

Purpose/Objective:

TBI is a radiotherapy technique used as part of the conditioning regimens for allogeneic bone marrow (BMT) or stem cell transplant (SCT). It has been proved the higher survival, and lower relapse risk following TBI plus etoposide compared with chemo conditioning alone 1 . To reduce the risk of acute and long-term side effects after conventional TBI, we created rival volumetric modulated (VMAT) TBI plans to conventional 2-dimensional ones. Feasibility and first dosimetric results were evaluated.

Material/Methods:

From June 2023, 3D TBI plans using VMAT technique were created in 5 pediatric patients who underwent TBI treatment. For the 3D plans, patients were simulated with a thermoplastic mask over the head and neck region and a full body vacuum bag for immobilization. Computed tomography (CT) images for the whole body were obtained with the acquisition of two patient’s orientation (head-first and foot-first), with a 5 mm slice thickness. The planning target volume (PTV) was defined as the entire body contracted to 5 mm below skin. The planning aims were to deliver a uniform dose of 12 Gy to the PTV, limiting the mean lung dose to < 9 Gy. Lung OAR was intended as the lung structure with a 1cm expansion into lungs organ to account for intra-fraction motion and ensure the full dose coverage of the ribs. The Eclipse 15.6 (Varian Medical System, Nederlands B.V.) treatment planning system was used to optimize VMAT beams. The PTV was split into two subsections from the top of the skull to mid-thigh and from mid-thigh to feet. From 5 to 7 total isocenters at head, thorax, abdomen, pelvis, mid-