Abstract ID: 87 Brachytherapy source and applicator models for diverse Monte Carlo simulations with egs_brachy

Thomson, Rowan M.; Chamberland, Marc; Deering, Stephen G.; Rogers, D. W. O.; Taylor, R. E. P.

doi:10.1016/j.ejmp.2017.09.045

Cited by 2 publications

(9 citation statements)

References 5 publications

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“…The source model was previously benchmarked 28 . The direction cosines (extracted as described in the previous paragraph) were used to determine source orientation as described in Section 11.4 of the egs_brachy manual 36 . The “superposition” run mode with dwell position weights corresponding to normalized dwell times was used.…”

Section: Acquisition and Validation Methodsmentioning

confidence: 99%

“…28 The direction cosines (extracted as described in the previous paragraph) were used to determine source orientation as described in Section 11.4 of the egs_brachy manual. 36 The "superposition" run mode with dwell position weights corresponding to normalized dwell times was used. Although egs_brachy can account for the volume of a voxel occupied by the source in each dwell position and only score dose in the part of the voxel not occupied by the source using the "volume correction" option, this option was not used in the final simulations because better consistency with MCNP calculations was achieved with this option off (i.e., "correction type = none" in the "source volume correction" block).…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

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A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

et al. 2023

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Purpose To provide the first clinical test case for commissioning of 192Ir brachytherapy model‐based dose calculation algorithms (MBDCAs) according to the AAPM TG‐186 report workflow. Acquisition and Validation Methods A computational patient phantom model was generated from a clinical multi‐catheter 192Ir HDR breast brachytherapy case. Regions of interest (ROIs) were contoured and digitized on the patient CT images and the model was written to a series of DICOM CT images using MATLAB. The model was imported into two commercial treatment planning systems (TPSs) currently incorporating an MBDCA. Identical treatment plans were prepared using a generic 192Ir HDR source and the TG‐43‐based algorithm of each TPS. This was followed by dose to medium in medium calculations using the MBDCA option of each TPS. Monte Carlo (MC) simulation was performed in the model using three different codes and information parsed from the treatment plan exported in DICOM radiation therapy (RT) format. Results were found to agree within statistical uncertainty and the dataset with the lowest uncertainty was assigned as the reference MC dose distribution. Data Format and Usage Notes The dataset is available online at http://irochouston.mdanderson.org/rpc/BrachySeeds/BrachySeeds/index.html,https://doi.org/10.52519/00005. Files include the treatment plan for each TPS in DICOM RT format, reference MC dose data in RT Dose format, as well as a guide for database users and all files necessary to repeat the MC simulations. Potential Applications The dataset facilitates the commissioning of brachytherapy MBDCAs using TPS embedded tools and establishes a methodology for the development of future clinical test cases. It is also useful to non‐MBDCA adopters for intercomparing MBDCAs and exploring their benefits and limitations, as well as to brachytherapy researchers in need of a dosimetric and/or a DICOM RT information parsing benchmark. Limitations include specificity in terms of radionuclide, source model, clinical scenario, and MBDCA version used for its preparation.

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Section: Acquisition and Validation Methodsmentioning

confidence: 99%

Section: Monte Carlo Simulationsmentioning

confidence: 99%

A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

et al. 2023

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“…10 Detailed descriptions of the egs_brachy MC code can be found in the study of Chamberland et al 10 and the egs_brachy user manual. 15 The egs_brachy MC application has also been benchmarked and validated against the extensively used BT MC code BrachyDOSE. 10,16,17 The Type B uncertainties of egs_brachy are recently compared to other state-of -the-art BT MC codes, PENELOPE-2018, and MCNP.…”

Section: Code Descriptionmentioning

confidence: 99%

“…This study also utilizes particle recycling; a variance reduction technique that reuses particles escaping from the source geometry an arbitrary number of times thus increasing the efficiency of the simulation. 15 Photons emitted from the source are recycled once, and each emitted photon is rotated by an arbitrary angle about the active length of the source (z-axis) prior to being recycled. Simulations that applied particle recycling are checked to ensure that the recycled particles do not result in nonindependent events and correlated data.…”

Section: Absorbed Dose Calculationmentioning

confidence: 99%

“…where τ (h) is the mean lifetime of the radionuclide (1/λ). 15 When a voxel in a scoring phantom is partially occupied by a seed, an MC voxel-volume correction technique is used to subtract the volume of the seed from the phantom's voxel. For accurate absorbed dose calculation, energy deposition is only scored in the portion of the voxel unoccupied by the seed.…”

Section: Absorbed Dose Calculationmentioning

confidence: 99%

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Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for ¹²⁵I prostate implants

et al. 2022

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Purpose: Monte Carlo (MC) simulation studies, aimed at evaluating the magnitude of tissue heterogeneity in 125 I prostate permanent seed implant brachytherapy (BT),customarily use clinical post-implant CT images to generate a virtual representation of a realistic patient model (virtual patient model).Metallic artifact reduction (MAR) techniques and tissue assignment schemes (TAS) are implemented on the post-implant CT images to mollify metallic artifacts due to BT seeds and to assign tissue types to the voxels corresponding to the bright seed spots and streaking artifacts, respectively. The objective of this study is to assess the combined influence of MAR and TAS on MC absorbed dose calculations in post-implant CT-based phantoms. The virtual patient models used for 125 I prostate implant MC absorbed dose calculations in this study are derived from the CT images of an external radiotherapy prostate patient without BT seeds and prostatic calcifications, thus averting the need to implement MAR and TAS. Methods: The geometry of the IsoSeed I25.S17plus source is validated by comparing the MC calculated results of the TG-43 parameters for the line source approximation with the TG-43U1S2 consensus data. Four MC absorbed dose calculations are performed in two virtual patient models using the egs_brachy MC code: (1) TG-43-based D w,w-TG43 , (2) D w,w-MBDC that accounts for interseed scattering and attenuation (ISA), (3) D m,m that examines ISA and tissue heterogeneity by scoring absorbed dose in tissue, and (4) D w,m that unlike D m,m scores absorbed dose in water. The MC absorbed doses (1) and ( 2) are simulated in a TG-43 patient phantom derived by assigning the densities of every voxel to 1.00 g cm −3 (water), whereas MC absorbed doses (3) and ( 4) are scored in the TG-186 patient phantom generated by mapping the mass density of each voxel to tissue according to a CT calibration curve. The MC absorbed doses calculated in this study are compared with VariSeed v8.0 calculated absorbed doses. To evaluate the dosimetric effect of MAR and TAS, the MC absorbed doses of this work (independent of MAR and TAS) are compared to the MC absorbed doses of different 125 I source models from previous studies that were calculated with different MC codes using post-implant CT-based phantoms generated by implementing MAR and TAS on post-implant CT images.

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Abstract ID: 87 Brachytherapy source and applicator models for diverse Monte Carlo simulations with egs_brachy

Cited by 2 publications

References 5 publications

A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for ¹²⁵I prostate implants

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Abstract ID: 87 Brachytherapy source and applicator models for diverse Monte Carlo simulations with egs_brachy

Cited by 2 publications

References 5 publications

A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

A MC‐based anthropomorphic test case for commissioning model‐based dose calculation in interstitial breast 192‐Ir HDR brachytherapy

Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for 125I prostate implants

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Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for ¹²⁵I prostate implants