Validation of a Monte Carlo prediction model for portal images using PENELOPE - Archive ouverte HAL Access content directly
Conference Poster Year : 2010

Validation of a Monte Carlo prediction model for portal images using PENELOPE

(1) , (1) , (1) , (1) , (2)
1
2

Abstract

In external beam radiotherapy, dosimetric verification is usually performed by comparing dose images provided by EPIDs with predicted images computed using Monte Carlo (MC) simulations. The goal of the present study is to develop a portal prediction model with the MC code PENELOPE and validate it against experiment. Experimental images were acquired at 12 MV using a Saturne 43 accelerator and a fluoroscopic Lynx2D EPID (SDD = 150 cm), for 4´4, 10´10 and 15´15 cm² open fields, and both without and with a 30´30´30 cm3 water phantom in the beam. The accelerator and the EPID were simulated with PENELOPE. Two EPID models were implemented, one describing in details the geometry and the other being a simplified model, composed of three layers (copper, GOS and water). The water layer simulated the backscatter within the EPID and its thickness had to be adjusted. The best EPID model was found to be the simplified model including an 8 cm thick backscatter compartment. This model was then used to compute portal images with and without the water phantom in the beam and the simulated and acquired images were compared using the g-analysis. g-index values less than 1 were obtained for 96% of the pixels for fields of 10x10 cm² or less and for 90% of the pixels for larger field sizes. These results exhibit that a simple MC EPID model allows predicting accurately portal images for open fields, with and without object in the beam, and that PENELOPE is a reliable tool for this purpose.
Fichier principal
Vignette du fichier
poster_DelphineLazaro_EPI2KX2010.pdf (523.38 Ko) Télécharger le fichier
Vignette du fichier
actes_DelphineLazaro_EPI2KX2010.pdf (25.73 Ko) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

cea-02558112 , version 1 (30-04-2020)

Identifiers

  • HAL Id : cea-02558112 , version 1

Cite

Delphine Lazaro-Ponthus, Juan-Carlos García Hernández, C. Driol, Bénédicte Poumarède, Samuel Legoupil. Validation of a Monte Carlo prediction model for portal images using PENELOPE. 11th international workshop on portal imaging (EPI2kX), Jun 2010, Leuven, Belgium. 88, pp.31 - 46, 2010. ⟨cea-02558112⟩
52 View
19 Download

Share

Gmail Facebook Twitter LinkedIn More