ESTRO 2023 - Abstract Book

S1781

Digital Posters

ESTRO 2023

London: The Royal College of Radiologists, 2021. Ref No. BFCO(21)1 (2) Appelt AL, Kerkhof EM, Nyvang L, et al. Robust dose planning objectives for mesorectal radiotherapy of early stage rectal cancer - A multicentre dose planning study. Tech Innov Patient Support Radiat Oncol. 2019;11:14-21. Published 2019 Oct 15.

PO-2008 Dosimetric comparison of Thoracic SBRT planning in Monaco and Eclipse for the Elekta Agility MLC.

R.J. Plata Villamizar 1 , M. Ribeiro 1 , C.K. Torzsok 1 , H. Broque 1 , A. Ruiz 1 , J.L. Rodriguez-Mongua 1 , J. Aponte 1 , F. Marangoni 1 , M. Pino 1

1 Fundación Arturo López Pérez, Radiotherapy, Santiago de Chile, Chile

Purpose or Objective Different solutions are being offered by vendors making multi-platform environments part of patient care. Treatment planning systems (TPS) are now capable of calculating dose for different vendors Linacs. Although these capabilities could benefit clinical workflow, care must be taken during implementation and validation, as algorithm model configuration and planning strategies are usually manufacturer dependent. Furthermore, when it comes to more modulated and complex plans such as SBRT, particularities during beam modeling and MLC configurations could increase dosimetric differences during planning. The purpose of this study is to provide a performance comparison between two treatment planning systems when calculating SBRT plans for Elekta VMAT. Materials and Methods A total of 10 targets, concerning 9 patients that were previously calculated in Monaco (V5.0) for an Elekta Synergy equipped with Agility MLC were selected for this study. Plans were recalculated in Eclipse (V.16.1) for the same machine using a twofold approach. Firstly, without limiting monitor units, and then applying the MU objective (MUO) tool during optimization, obtaining similar dosimetric results for the two approaches. In order to streamline the process and facilitate plan comparison, organs at risk dose values obtained in Monaco were considered as objective goals during optimization in Eclipse. Modulation factors (MF) were recorded as indicators for plan complexity in both systems. RTOG parameters R50 and D2cm were also logged to account for lower dose control capabilities. Results The average target was 28.48 cc. The average of the results obtained with respect to D98%, D2% and Dmean are the following: in Monaco 96.73%, 119.40% and 109.74%, in Eclipse 96.82%, 111.27% and 105.45%, respectively. Modulation factors obtained in Monaco and Eclipse are illustrated in Figure 1. Figure 2 illustrates differences in R50 and D2cm for both systems.

Figure 1. Modulation factors obtained in Monaco and Eclipse