Modified COMS plaques for 125I and 103Pd iris melanoma brachytherapy.

Novel plaques are used to treat iris melanoma at the Mayo Clinic Rochester. The plaques are a modification of the Collaborative Ocular Melanoma Study (COMS) 22 mm plaque design with a gold alloy backing, outer lip, and silicone polymer insert. An inner lip surrounds a 10 mm diameter cutout region at the plaque center. Plaques span 360°, 270°, and 180° arcs. This article describes dosimetry for these plaques and others used in the treatment of anterior eye melanomas. The EGSnrc user-code BrachyDose is used to perform Monte Carlo simulations. Plaques and seeds are fully modeled. Three-dimensional dose distributions for different plaque models, TG-43 calculations, and (125)I (model 6711) and (103)Pd (model 200) seeds are compared via depth-dose curves, tabulation of doses at points of interest, and isodose contours. Doses at points of interest differ by up to 70% from TG-43 calculations. The inner lip reduces corneal doses. Matching plaque arc length to tumor extent reduces doses to eye regions outside the treatment area. Maintaining the same prescription dose, (103)Pd offers lower doses to critical structures than (125)I, with the exception of the sclera adjacent to the plaque. The Mayo Clinic plaques offer several advantages for anterior eye tumor treatments. Doses to regions outside the treatment area are significantly reduced. Doses differ considerably from TG-43 predictions, illustrating the importance of complete Monte Carlo simulations. Calculations take a few minutes on a single CPU, making BrachyDose sufficiently fast for routine clinical treatment planning.

Thomson RM ，Furutani KM ，Pulido JS ，Stafford SL ，Rogers DW ... -  《-》

Monte Carlo dosimetry for 125I and 103Pd eye plaque brachytherapy with various seed models.

Thomson RM ，Rogers DW 《MEDICAL PHYSICS》

Monte Carlo dosimetry for 125I and 103Pd eye plaque brachytherapy.

Thomson RM ，Taylor RE ，Rogers DW 《-》

Improved treatment planning for COMS eye plaques.

Astrahan MA 《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

Monte Carlo dosimetry for 103Pd, 125I, and 131Cs ocular brachytherapy with various plaque models using an eye phantom.

Lesperance M ，Martinov M ，Thomson RM 《-》