COMS eye plaque brachytherapy dosimetry simulations for 103Pd, 125I, and 131Cs.
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 carrying 103Pd, 125I, and 131Cs radionuclides, respectively, were modeled and benchmarked against previously published values. Calculated dose rate constants MClambda were 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% for 103Pd, 125I, and 131Cs, 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.
Melhus
Christopher S
CS
Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA. cmelhus@tuftsmedicalcenter.org
Rivard
Mark J
MJ
D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D002588:Cesium Radioisotopes / Q000627:therapeutic use*; D003198:Computer Simulation; D004867:Equipment Design; D005123:Eye / Q000528:radiation effects; D005134:Eye Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D010165:Palladium / Q000627:therapeutic use*; D017785:Photons; D011868:Radioisotopes / Q000627:therapeutic use*; D011874:Radiometry / Q000379:methods*; D012984:Software; D013997:Time Factors
D002588:Cesium Radioisotopes; D007457:Iodine Radioisotopes; D011868:Radioisotopes; D010165:Palladium