Determination of dosimetric characteristics of OptiSeed(TM) a plastic brachytherapy (103)Pd source.

A new (103)Pd plastic brachytherapy source, OptiSeed(TM) Model 1032P, is being introduced by International Brachytherapy sa (IBt). Measurements of the dose distributions about the source were performed using LiF thermoluminescent dosimeters (TLD-100) in Virtual Water(TM). MCNP5 calculations were performed to determine the dose distributions in Virtual Water(TM) and liquid water. The source dose rate constant, radial dose function, anisotropy function and anisotropy factor have been determined following the updated AAPM TG-43 recommendations. The measured dose rate constant in the Virtual Water(TM) phantom was determined to be 0.727+/-6.9% cGyh(-1)U(-1), and the computed value is 0.716+/-2.1% cGyh(-1)U(-1). The Monte-Carlo simulation yielded a dose rate constant of 0.665+/-2.1% cGyh(-1)U(-1) in water. The measured dose rate constant in water is 0.675+/-7.5% cGyh(-1)U(-1). It is determined by multiplying the dose rate constant measured in the Virtual Water(TM) phantom with the ratio of the value calculated in water to that in Virtual Water(TM). The average of the measured and calculated dose rate constant is 0.670+/-5.5% cGyh(-1)U(-1). The radial dose functions of the new source were measured for distances ranging from 1 to 7 cm in a Virtual Water(TM) phantom. The anisotropy functions in Virtual Water(TM) phantom were measured for distances of 2, 3, 5, and 7 cm. The Monte-Carlo computed radial dose functions, anisotropy functions, and anisotropy factors in both Virtual Water(TM) phantom and water are reported.