Technical notes| Volume 31, ISSUE 3, P301-306, May 2015

Monte Carlo modeling of the Siemens Optifocus multileaf collimator

Published:February 13, 2015DOI:


      • We developed a new component module (SMLC) for the BEAMnrc Monte Carlo package.
      • We validated SMLC via geometric checks and comparing it with the VARMLC module.
      • We tuned the SMLC parameters so that it fits the Optifocus MLC of our hospital.
      • Measurements of tongue-and-groove fields agreed well with simulations.
      • We proved that SMLC is clinically relevant by simulating a real patient IMRT field.


      We have developed a new component module for the BEAMnrc software package, called SMLC, which models the tongue-and-groove structure of the Siemens Optifocus multileaf collimator. The ultimate goal is to perform accurate Monte Carlo simulations of the IMRT treatments carried out with Optifocus. SMLC has been validated by direct geometry checks and by comparing quantitatively the results of simulations performed with it and with the component module VARMLC. Measurements and Monte Carlo simulations of absorbed dose distributions of radiation fields sensitive to the tongue-and-groove effect have been performed to tune the free parameters of SMLC. The measurements cannot be accurately reproduced with VARMLC. Finally, simulations of a typical IMRT field showed that SMLC improves the agreement with experimental measurements with respect to VARMLC in clinically relevant cases.

      PACS number

      87.55. K-


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