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Dosimetry revisited for the HDR I 192 r brachytherapy source model mHDR‐v2
Author(s) -
Granero Domingo,
Vijande Javier,
Ballester Facundo,
Rivard Mark J.
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3531973
Subject(s) - dosimetry , brachytherapy , monte carlo method , imaging phantom , kerma , voxel , nuclear medicine , physics , radiation , computational physics , radiation treatment planning , medical physics , computer science , optics , radiation therapy , mathematics , statistics , medicine , radiology , artificial intelligence
Purpose: Recently, the manufacturer of the HDR I192 r mHDR‐v2 brachytherapy source reported small design changes (referred to herein as mHDR‐v2r) that are within the manufacturing tolerances but may alter the existing dosimetric data for this source. This study aimed to (1) check whether these changes affect the existing dosimetric data published for this source; (2) obtain new dosimetric data in close proximity to the source, including the contributions fromI192 r electrons and considering the absence of electronic equilibrium; and (3) obtain scatter dose components for collapsed cone treatment planning system implementation. Methods: Three different Monte Carlo (MC) radiation transport codes were used: MCNP5 , PENELOPE2008 , and GEANT4 . The source was centrally positioned in a 40 cm radius water phantom. Absorbed dose and collision kerma were obtained using 0.1 mm (0.5 mm) thick voxels to provide high‐resolution dosimetry near (far from) the source. Dose‐rate distributions obtained with the three MC codes were compared. Results: Simulations of mHDR‐v2 and mHDR‐v2r designs performed with three radiation transport codes showed agreement typically within 0.2% for r ≥ 0.25 cm . Dosimetric contributions from source electrons were significant for r < 0.25 cm . The dose‐rate constant and radial dose function were similar to those from previous MC studies of the mHDR‐v2 design. The 2D anisotropy function also coincided with that of the mHDR‐v2 design for r ≥ 0.25 cm . Detailed results of dose distributions and scatter components are presented for the modified source design. Conclusions: Comparison of these results to prior MC studies showed agreement typically within 0.5% for r ≥ 0.25 cm . If dosimetric data for r < 0.25 cm are not needed, dosimetric results from the prior MC studies will be adequate.