Integral-transport-based deterministic brachytherapy dose calculations

Zhou, Chuanyu; Inanc, Feyzi

doi:10.1088/0031-9155/48/1/306

Cited by 14 publications

(10 citation statements)

References 92 publications

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“…Some other work based on the integral transport equation has been performed by Zhou and Inanc. [15][16][17] Some features of the algorithm used in this work are introduced in the following sections.…”

Section: Methodsmentioning

confidence: 99%

“…The details of the computational algorithm implemented for the photon transport can be found in a previous article. 17 One of the new additions not covered in those articles is the fluorescence radiation. In addition to the inclusion of this physical mechanism, we also redesigned the algorithm for parallel processing.…”

Section: A Governing Equationsmentioning

confidence: 99%

“…As discussed in a previous article, the primary flux is computed by approximating the surface source by a collection of point sources. 17 Figure 1 ensure that any heterogeneity in the problem domain can be sampled properly. These heterogeneities can be voids, tissue property variations, or another seed between the primary seed and the point at which the primary flux is being computed.…”

Section: Parallel Algorithmmentioning

confidence: 99%

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Distortions induced by radioactive seeds into interstitial brachytherapy dose distributions

2004

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In a previous article, we presented development and verification of an integral transport equation-based deterministic algorithm for computing three-dimensional brachytherapy dose distributions. Recently, we have included fluorescence radiation physics and parallel computation to the standing algorithms so that we can compute dose distributions for a large set of seeds without resorting to the superposition methods. The introduction of parallel computing capability provided a means to compute the dose distribution for multiple seeds in a simultaneous manner. This provided a way to study strong heterogeneity and shadow effects induced by the presence of multiple seeds in an interstitial brachytherapy implant. This article presents the algorithm for computing fluorescence radiation, algorithm for parallel computing, and display results for an 81-seed implant that has a perfect and imperfect lattice. The dosimetry data for a single model 6711 seeds is presented for verification and heterogeneity factor computations using simultaneous and superposition techniques are presented.

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Section: Methodsmentioning

confidence: 99%

Section: A Governing Equationsmentioning

confidence: 99%

Section: Parallel Algorithmmentioning

confidence: 99%

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Distortions induced by radioactive seeds into interstitial brachytherapy dose distributions

2004

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“…Because these methods are all based on phasespace discretization, TG-186 categorizes them as grid-based Boltzmann equation solvers (GBBS). Zhou and Inanc developed a GBBS, which they applied to LE brachytherapy, 64 based on direct evaluation of the integral LBTE, expanded in orders of scattering. Daskalov et al applied a 2D discreteordinates GBBS (from DANTSYS) (Ref.…”

Section: Iib2 Deterministic Solutions To the Linear Boltzmann Tranmentioning

confidence: 99%

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

et al. 2012

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The charge of Task Group 186 (TG-186) is to provide guidance for early adopters of model-based dose calculation algorithms (MBDCAs) for brachytherapy (BT) dose calculations to ensure practice uniformity. Contrary to external beam radiotherapy, heterogeneity correction algorithms have only recently been made available to the BT community. Yet, BT dose calculation accuracy is highly dependent on scatter conditions and photoelectric effect cross-sections relative to water. In specific situations, differences between the current water-based BT dose calculation formalism (TG-43) and MBDCAs can lead to differences in calculated doses exceeding a factor of 10. MBDCAs raise three major issues that are not addressed by current guidance documents: (1) MBDCA calculated doses are sensitive to the dose specification medium, resulting in energy-dependent differences between dose calculated to water in a homogeneous water geometry (TG-43), dose calculated to the local medium in the heterogeneous medium, and the intermediate scenario of dose calculated to a small volume of water in the heterogeneous medium. (2) MBDCA doses are sensitive to voxel-by-voxel interaction cross sections. Neither conventional single-energy CT nor ICRU∕ICRP tissue composition compilations provide useful guidance for the task of assigning interaction cross sections to each voxel. (3) Since each patient-source-applicator combination is unique, having reference data for each possible combination to benchmark MBDCAs is an impractical strategy. Hence, a new commissioning process is required. TG-186 addresses in detail the above issues through the literature review and provides explicit recommendations based on the current state of knowledge. TG-43-based dose prescription and dose calculation remain in effect, with MBDCA dose reporting performed in parallel when available. In using MBDCAs, it is recommended that the radiation transport should be performed in the heterogeneous medium and, at minimum, the dose to the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim ...

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“…The RMS difference over the entire plane of comparison was 1.95%. Zhou et al have solved the LBTE for a single 6711 125 I seed 3 and an 81 seed implant 4 to study distortions induced by interseed and intraseed attenuation and reported results within Ϯ5% of Monte Carlo. Calculation time for the single seed case was approximately 42 min whereas the calculation time for the 81 seed case was 35 h on two processors.…”

Section: Introductionmentioning

confidence: 99%

Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose‐rate brachytherapy source

et al. 2008

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The goal of this work was to calculate the dose distribution around a high dose-rate 192Ir brachytherapy source using a multi-group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila version 6.1.1 was used to calculate the photon kerma rate distribution in water around the Nucletron microSelectron mHDRv2 source. MCNPX 2.5.c was used to compute the Monte Carlo water photon kerma rate distribution. Two hundred million histories were simulated, resulting in standard errors of the mean of less than 3% overall. The number of energy groups, S(n) (angular order), P(n) (scattering order), and mesh elements were varied in addition to the method of analytic ray tracing to assess their effects on the deterministic solution. Water photon kerma rate matrices were exported from both codes into an in-house data analysis software. This software quantified the percent dose difference distribution, the number of points within +/- 3% and +/- 5%, and the mean percent difference between the two codes. The data demonstrated that a 5 energy-group cross-section set calculated results to within 0.5% of a 15 group cross-section set. S12 was sufficient to resolve the solution in angle. P2 expansion of the scattering cross-section was necessary to compute accurate distributions. A computational mesh with 55 064 tetrahedral elements in a 30 cm diameter phantom resolved the solution spatially. An efficiency factor of 110 with the above parameters was realized in comparison to MC methods. The Attila code provided an accurate and efficient solution of the Boltzmann transport equation for the mHDRv2 source.

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Integral-transport-based deterministic brachytherapy dose calculations

Cited by 14 publications

References 92 publications

Distortions induced by radioactive seeds into interstitial brachytherapy dose distributions

Distortions induced by radioactive seeds into interstitial brachytherapy dose distributions

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose‐rate brachytherapy source

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