A CT-based Monte Carlo simulation tool for dosimetry planning and analysis

J. J. DeMarco, T. D. Solberg, J. B. Smathers

Research output: Contribution to journalArticlepeer-review

182 Scopus citations


The Los Alamos code MCNP4A (Monte Carlo N-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. A graphical user interface has been developed that automatically sets up the MCNP4A geometry and radiation source requirements for a three-dimensional Monte Carlo simulation using computed tomography data. The major drawback for this dosimetry system is the amount of time to obtain a statistically significant answer. A specialized patch file has been developed that optimizes photon particle transport and dose scoring within the standard MCNP4A lattice geometry. The transport modifications produce a performance increase (number of histories per minute) of approximately 4.7 based upon a 6 MV point source centered within a 30>(30X 30 cm3 lattice water phantom and 1 x 1 x 1 mm3 voxels. The dose scoring modifications produce a performance increase of approximately 470 based upon a tally section of greater than 1 x 104 lattice elements and a voxel size of 5 mm3. Homogeneous and heterogeneous benchmark calculations produce good agreement with measurements using a standard water phantom and a high- and low-density heterogeneity phantom. The dose distribution from a typical mediastinum treatment planning setup is presented for qualitative analysis and comparison versus a conventional treatment planning system.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalMedical physics
Issue number1
StatePublished - Jan 1998


  • Computed tomography
  • Dosimetry
  • Inhomogeneity
  • Monte Carlo
  • Treatment planning

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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