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COMS eye plaque brachytherapy dosimetry simulations for P 103 d , I 125 , and C 131 s
Author(s) -
Melhus Christopher S.,
Rivard Mark J.
Publication year - 2008
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 - 10.1118/1.2940604
Subject(s) - brachytherapy , dosimetry , monte carlo method , nuclear medicine , homogeneous , materials science , optics , chemistry , biomedical engineering , physics , radiation therapy , medicine , mathematics , radiology , thermodynamics , statistics
Monte Carlo (MC) simulations were performed to estimate brachytherapy dose distributions for Collaborative Ocular Melanoma Study (COMS) eye plaques. Brachytherapy seed models 200, 6711, and CS‐1 Rev2 carryingP103 d ,I125, andC131 s radionuclides, respectively, were modeled and benchmarked against previously published values. Calculated dose rate constantsΛMCwere 0.684, 0.924, and 1.052 cGy h − 1 U − 1( ± 2.6 % , k = 1 uncertainty) for models 200, 6711, and CS‐1 Rev2, respectively. The seeds were distributed into 10, 12, 14, 16, 18, 20, and 22 mm‐diameter COMS eye plaques. Simulations were performed in both heterogeneous and homogeneous environments, where the latter were in‐water and the former included the silastic seed carrier insert and gold‐alloy plaque. MC‐based homogenous central axis dose distributions agreed within 2 % ± 1 %( ± 1 s . d . )to hand‐calculated values. For heterogeneous simulations, notable photon attenuation was observed, with dose reduction at 5 mm of 19%, 11%, and 9% forP103 d ,I125, andC131 s , respectively. A depth‐dependent correction factor was derived to correct homogenous central‐axis dose distributions for plaque component heterogeneities, which were found to be significant at short radial distances.