Benchmarking BrachyDose: Voxel based EGSnrc Monte Carlo calculations of TG-43 dosimetry parameters

Ottawa Carleton Institute of Physics, Carleton University, Ottawa, Canada KIS 5B6.
Medical Physics (Impact Factor: 2.64). 03/2007; 34(2):445-57. DOI: 10.1118/1.2400843
Source: PubMed


In this study, BrachyDose, a recently developed EGSnrc Monte Carlo code for rapid brachytherapy dose calculations, has been benchmarked by reproducing previously published dosimetry parameters for three brachytherapy seeds with varied internal structure and encapsulation. Calculations are performed for two 125I seeds (Source Tech Medical Model STM1251 and Imagyn isoSTAR model 12501) and one l03Pd source (Theragenics Model 200). Voxel size effects were investigated with dose distribution calculations for three voxel sizes: 0.1 x 0.1 x 0.1 mm(3), 0.5 x 0.5 x 0.5 mm(3), and 1 X 1 X 1 mm(3). In order to minimize the impact of voxel size effects, tabulated dosimetry data for this study consist of a combination of the three calculations: 0.1 X 0.1 x 0.1 mm(3) voxels for distances in the range of 0<r< or = l cm, 0.5 x0.5 0.5 mm(3) voxels for 1 <r< or =5 cm and 1 x 1 X 1 mm(3) voxels for 5<r< or = 10 cm. Dosimetry parameters from this study are compared with values calculated by other authors using Williamson's PTRAN code and to measured values. Overall, calculations made with Brachydose show good agreement with calculations made with PTRAN although there are some exceptions.

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    • "Task group 138 (DeWerd et al., 2011) also emphasized the need to explain the statistical results and provide uncertainty analyses in MC simulations as well as measurements of Brachytherapy quantities. Recent literatures (Taylor and Rogers, 2008; Ballester et al., 2009; Poon and Verhaegen, 2009; Wang and Li, 2002; Baltas et al., 2001; Moura et al., 2014; Daskalov et al., 2000; Taylor et al., 2007; Cho et al., 1999; Russell et al., 2005; Angelopoulos et al., 2000; Patel et al., 2004) report on dosimetrical parameters for 192 Ir. However, detailed error analysis or statistical discussion is still required. "
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    ABSTRACT: The Geant4 Monte Carlo MC associated Brachytherapy example was adapted, enhanced and several analysis techniques have been developed. The simulation studies the isodose distribution of the total, primary and scattered doses around a Nucletron microSelectron 192Ir source. Different phantom materials were used (water, tissue and bone) and the calculation was conducted at various depths and planes. The work provides an early estimate of the required number of primary events to ultimately achieve a given uncertainty at a given distance, in the otherwise CPU and time consuming clinical MC calculation. The adaptation of the Geant4 toolkit and the enhancements introduced to the code are all validated including the comprehensive decay of the 192Ir source, the materials used to build the geometry, the geometry itself and the calculated scatter to primary dose ratio. The simulation quantitatively illustrates that the scattered dose in the bone medium is larger than its value in water and tissue. As the distance away from the source increases, scatter contribution to dose becomes more significant as the primary dose decreases. The developed code could be viewed as a platform that contains detailed dose calculation model for clinical application of HDR 192Ir in Brachytherapy.
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    • "Besides small differences that in view of the physics underlying the low energy regime of 125I photon emissions render every source design unique in terms of dosimetry, the new IsoSeed I25.S17plus design is comparable to that of the OncoSeed 6711 [4, 6], SelectSeed 130.002 [8], Advantage IAI-125A [7], I-Seed AgX100 [9], and ThinSeed 9011 [5, 6] sources. It is also comparable to its predecessors in the IsoSeed series, I25.S17 [2] and I25.S06 [1], as well as Best 2301 [7], with the exception of marker material which is Molybdenum, Gold and Tungsten, respectively, instead of silver. "
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    ABSTRACT: To determine the relative dose rate distribution around the new (125)I brachytherapy source IsoSeed I25.S17plus and report results in a form suitable for clinical use. Results for the new source are also compared to corresponding results for other commercially available (125)I sources of similar design. Monte Carlo simulations were performed using the MCNP5 v.1.6 general purpose code. The model of the new source was prepared from information provided by the manufacturer and verified by imaging a sample of ten non-radioactive sources. Corresponding simulations were also performed for the 6711 (125)I brachytherapy source, using updated geometric information presented recently in the literature. The uncertainty of the dose distribution around the new source, as well as the dosimetric quantities derived from it according to the Task Group 43 formalism, were determined from the standard error of the mean of simulations for a sample of fifty source models. These source models were prepared by randomly selecting values of geometric parameters from uniform distributions defined by manufacturer stated tolerances. Results are presented in the form of the quantities defined in the update of the Task Group 43 report, as well as a relative dose rate table in Cartesian coordinates. The dose rate distribution of the new source is comparable to that of sources of similar design (IsoSeed I25.S17, Oncoseed 6711, SelectSeed 130.002, Advantage IAI-125A, I-Seed AgX100, Thinseed 9011). Noticeable differences were observed only for the IsoSeed I25.S06 and Best 2301 sources.
    Full-text · Article · Dec 2013 · Journal of Contemporary Brachytherapy
    • "The results of radial dose function in our study using EGSnrc code show an agreement of within ±2% with the data derived by Taylor et al.[10] This ±2% deviation in radial dose function might be due to the differences in voxels size and the number of histories used in the simulation.[31] The results of radial dose function derived by three different methods using 0.1-cc chamber show an agreement within ±3% up to a radial distance of 12.0 cm; after that, for the larger distances it increases up to ±5%. "
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    ABSTRACT: The comparative dosimetry of GammaMed (GM) Plus high-dose rate brachytherapy source was performed by an experiment using 0.1-cc thimble ionization chamber and simulation-based study using EGSnrc code. In-water dose measurements were performed with 0.1-cc chamber to derive the radial dose function (r = 0.8 to 20.0 cm) and anisotropy function (r = 5.0 cm with polar angle from 10° to 170°). The nonuniformity correction factor for 0.1-cc chamber was applied for in-water measurements at shorter distances from the source. The EGSnrc code was used to derive the dose rate constant (Λ), radial dose function g(L)(r) and anisotropy function F(r, θ) of GM Plus source. The dosimetric data derived using EGSnrc code in our study were in very good agreement relative to published data for GM Plus source. The radial dose function up to 12 cm derived from measured dose using 0.1-cc chamber was in agreement within ±3% of data derived by the simulation study.
    No preview · Article · Jul 2010 · Journal of Medical Physics
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