[Brachytherapy using Ru-106 applicators in ophthalmology].

Two Ru-106 applicators of the type CCB as manufactured by the "Zentralinstitut für Isotopen- und Strahlenforschung" (Berlin, GDR) were investigated. The homogeneity of the relative dose distribution at the surface of the applicators was determined. For the evaluation of the data extremely small TLD crystals (2 x 1 x 1 mm) had to be manufactured as well as an almost tissue equivalent acrylic eye phantom. In order to assure reproducibility of the applicator positioning, the plaque suture eyelets had to be placed on locating pins. 120 points of measurements located within the active plaque area of 20 mm diameter were evaluated. The results show that the area to be used in tumor treatment is about 20 to 25% less than expected. One plaque shows a considerable inhomogeneity with respect to dose distribution (up to 40%). A modified eye phantom was used for the determination of the central axis depth dose distribution.