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SU‐E‐T‐354: Dosimetry Parameters Revisited for the IsoAid Model IAI‐125A Brachytherapy Seed
Author(s) -
Aryal P,
Molloy J,
Rivard M
Publication year - 2013
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 - 10.1118/1.4814788
Subject(s) - dosimetry , brachytherapy , monte carlo method , nuclear medicine , physics , dose rate , photon , computational physics , radiation , mathematics , optics , medical physics , statistics , medicine , radiation therapy , radiology
Purpose: Investigate and analyze TG43 dosimetry parameters for the IsoAid I 125 model IAI 125A seed Methods: We revisited dosimetry for the IsoAid advantage I 125 model IAI 125A seed to verify the published TG43 parameters. The IsoAid seed was examined based on manufacturer data and detailed information published in literature. The MCNP5 Monte Carlo radiation transport code was used. Sensitivity of these dosimetry parameters was assessed by changing a total of 10 geometric and computational variables, including source coating thickness, capsule design, photon emission spectrum, and cross section library. The calculated dose rate constants and radial dose functions were then compared with published literature values. Results: Compared to the reference simulation conditions of a 0.5 um source coating, recent capsule design data, the NNDC photon spectrum, and the ZAID.04p MCNP5 cross section libraries, the highest dose rate constant variation was +3.1% and the lowest was −4.0% compared to our value of 0.922 cGy/h/U. Calculated values by Solberg et al. (2002) and Meigooni et al. (2002) were 0.962 and 0.98 cGy/h/U respectively. There were significant differences (>10%) between the published values for the radial dose function and those calculated herein, becoming increasingly disparate as radial distance increased. These differences could be explained within a few percent by performing simulations with their photon emission spectrum and using older cross section libraries. For the similarly designed model 6711 seed, our dose rate constant results agreed within 0.2% and within 0.5% for gL(0.5