Last vertex splitting: a new retroactive Monte Carlo splitting technique applied to LINAC out-of-field dose computation.

Journal: Physics in medicine and biology
Published Date:

Abstract

We propose a new variance reduction technique called last vertex splitting (LVS) designed to reduce computation time in Monte Carlo (MC) simulations for particles traversing high-attenuating media, such as the collimator and other beam-limiting devices in a LINAC head. Combined with a hybrid version of the track length estimator (hTLE), the LVS method accelerates out-of-field (OOF) dose calculations by optimizing photon tracking and interaction modeling. Our analysis indicates that the residual bias introduced by the method remains below one percent, with an estimated efficiency speed-up of ×4.5 for a 10×10 cmfield, to ×10 when combined with hTLE. Typically, this approach enables the rapid generation of extensive MC datasets, facilitating the training of deep learning algorithms to predict OOF doses more efficiently. Beyond radiotherapy applications, the LVS method can be adapted for scenarios requiring computationally efficient simulations of particle transport in complex geometries, such as in radiation shielding assessments.

Authors

  • Maxime Jacquet
    Centre Léon Bérard, CREATIS, 28 rue Laënnec, LYON, 69373, FRANCE.
  • Jean Michel Létang
    CREATIS, 21 Av. Jean Capelle O, Villeurbanne, 69621, FRANCE.
  • Jean Michel Létang
    CREATIS; CNRS UMR 5220; INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France.
  • Thomas Baudier
    Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, Inserm, Lyon, France.
  • Philippe Boissard
    , Centre Léon Bérard, 28 Rue Laënnec, Lyon, 69373, FRANCE.
  • Meissane M'hamdi
    Unité Mixte de Recherche (UMR) 1030 Radiothérapie Moléculaire et Innovation Thérapeutique, ImmunoRadAI, Inserm, Université Paris-Saclay, Institut Gustave Roussy, Villejuif, France; Department of Radiation Oncology, Institut Gustave Roussy, Villejuif, France.
  • Ibrahima Diallo
    Unité Mixte de Recherche (UMR) 1030 Radiothérapie Moléculaire et Innovation Thérapeutique, ImmunoRadAI, Inserm, Université Paris-Saclay, Institut Gustave Roussy, Villejuif, France; Department of Radiation Oncology, Institut Gustave Roussy, Villejuif, France.
  • Charlotte Robert
    U1030 Molecular Radiotherapy, Paris-Sud University - Gustave Roussy - Inserm - Paris-Saclay University, Villejuif, France; Department of Medical Physics, Gustave Roussy - Paris-Saclay University, Villejuif, France. Electronic address: ch.robert@gustaveroussy.fr.
  • David Sarrut
    Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1294, INSA-Lyon, Université Lyon 1, Lyon, France.