Validation of the collapsed cone algorithm for HDR liver brachytherapy against Monte Carlo simulations

Anna Sophie Duque, Teun van Wagenberg, Max Seidensticker, Florian Streitparth, Franziska Walter, Katia Parodi, Frank Verhaegen, Jens Ricke, Claus Belka, Gabriel Paiva Fonseca, Stefanie Corradini, Guillaume Landry*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


PURPOSE: To validate the collapsed cone (CC) algorithm against Monte Carlo (MC) simulations for model-based dose calculations in high-dose-rate (HDR) liver brachytherapy.

METHODS AND MATERIALS: Doses for liver brachytherapy treatment plans of 10 cases were retrospectively recalculated with a model-based approach using Monte Carlo n-Particle Code (MCNP) 6 (Dm,m-MC) and Oncentra Brachy ACE (Dm,m-ACE). Tissue segmentation consisted of assigning uniform compositions and mass densities to predefined Hounsfield Unit (HU) thresholds. Resulting doses were compared according to dose volume histogram parameters typical for clinical routine. These included the percentage liver volume receiving 5 Gy (V5Gy) or 10 Gy (V10Gy), the maximum dose to one cubic centimeter (D1cc) of organs at risk, the clinical target volume (CTV) fractions receiving 150% (V150), 100% (V100), 95% (V95) and 90% (V90) of the prescribed dose and the absolute doses to 95% (D95) and 90% (D90) of the CTV volumes.

RESULTS: Doses from Oncentra Brachy ACE agreed well with MC simulations. Differences were seen far from the source, in low-density regions and bone structures. Median percentage deviations were 1.1% for the liver V5Gy and 0.4% for the liver V10Gy, with deviations of largest magnitude amounting to 2.2% and 1.0%, respectively. Organs at risk had median deviations ranging from 0.3% to 1.5% for D1cc, with outliers ranging up to 4.6%. CTV volume parameter deviations ranged between -1.5% and 0.5%, dose parameter deviations ranged mostly between -2% and 1%, with two outliers at -4.0% and -3.4% for a small CTV.

Original languageEnglish
Pages (from-to)936-947
Number of pages12
Issue number4
Publication statusPublished - 19 May 2021


  • AAPM
  • AAPM TG-186
  • Collapsed cone
  • IR-192
  • Interstitial liver brachytherapy
  • Model-based dose calculation algorithm
  • Monte Carlo Simulation
  • Radiotherapy
  • TG-43

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