ESTRO 2023 - Abstract Book

S1526

Digital Posters

ESTRO 2023

Conclusion The penalty score based on the mean absolute dose deviation has proven to be a useful tool to evaluate the DVH and whose results agree with previous works. Both VMAT and HT can provide more uniform target doses as compared to F-F IMRT. Helical TomoTherapy is superior to IMRT and VMAT in preserving OARs and planning quality parameters, as previous studies have shown (Rao et al,2010).

PO-1801 Monte Carlo Modeling of the Siemens® ARTISTE™ 160 Multi-leaf Collimator for IMRT dose verification

M. dayyani 1 , E. Hoseinian-Azghadi 2 , L. Rafat-Motavalli 3 , H. Miri-Hakimabad 3 , T. Tu ğ rul 4 , L. Sobhkhiz-Sabet 5

1 Reza Radiotherapy and Oncology Center, Radiation Oncology Department, Mashhad, Iran Islamic Republic of; 2 Reza Radiotherapy and Oncology Center, Research and Education Department, Mashhad, Iran Islamic Republic of; 3 Ferdowsi University of Mashhad, Physics Department, Faculty of Science, Mashhad, Iran Islamic Republic of; 4 Medicine Faculty of Van Yüzüncü Yıl University, Department of Radiation Oncology, Van, Turkey; 5 Reza Radiotherapy and Oncology Center, Medical Physics Department, Mashhad, Iran Islamic Republic of Purpose or Objective This study aimed to develop a Monte Carlo (MC) model for the Siemens® ARTISTE™ 160 Multi-leaf Collimator (MLC) and to determine the level of complexity needed to model MLCs for application in intensity modulated radiotherapy (IMRT) dose verification. Materials and Methods To describe the Siemens Artiste 160 MLC in the MCNPX code, three different levels of complexity were considered. The first and the simplest model consists of rectangular shaped leaves with no air gap between two adjacent leaves. In the second model, the tilt angle and the air gap between two adjacent leaves were considered. The third and the most sophisticated one is the detailed model in which the leaf tips with curved edges are simulated (see Figure 1). The MC modeling was validated by comparing the calculated dose distribution (both MC-based and TPS-based) with EBT3 film measurements. In this comparison, there are three MC-based data sets for different levels of MLC modeling complexity, and two from common treatment planning systems; Prowess Panther and RayStation. Comparisons were made based on 2D Gamma passing rate (GPR, 3%⁄2 mm), for four static test fields, and ten complicated beam segments of patient-specific IMRT plans.

Results In case of simple and quite large fields, GPR of 98% was obtained for the TPS-based and MC-based (all 3 models) calculated data points. For more complex fields, only MC modelling which include MLC tilt angle could estimate dose data with GPR of > 90%. For the fields with MLC gap (between two opposite leaves) less than 20 mm, the detailed MC modelling was needed to keep the GPR value greater than 95%. TPS-based dose estimations showed agreement within 88%-97% for all complex fields. However, the detailed MC model is superior to the TPS model of MLC particularly for the fields with small MLC gaps. Conclusion The Siemens® ARTISTE™ linac equipped with 160 MLC was successfully modeled using MCNPX 2.6.0 Monte Carlo code. The needed complexity of the model was investigated by comparing the MC-based and TPS-based calculated data with experiments. The detailed MC model can be applied as an independent patient dose validation system.

PO-1802 Deep Particles Embedding: accelerating Monte-Carlo dose simulations

S. Martinot 1 , N. Komodakis 2 , M. Vakalopoulou 3 , N. Bus 1 , C. Robert 4 , E. Deutsch 4 , N. Paragios 5

1 Therapanacea, Physics, Paris, France; 2 University of Crete, Computer Vision, Heraklion, Greece; 3 Centralesupelec, MATHEMATICS AND INFORMATICS, Gif-sur-Yvette, France; 4 Institut Gustave Roussy, Radiotherapy, Villejuif, France; 5 Therapanacea, CEO, Paris, France Purpose or Objective The Monte-Carlo (MC) radiation transport calculation method remains the most accurate tool available to account for particles-matter interaction and therefore, for simulating radiotherapy dose distribution maps. However, without heavy