NUKLEONIKA 2005, 50(1):17-22

The deposition of iodine-125 on silver bars to be sealed in titanium capsules as seed-type sources for brachytherapy was studied. For this purpose, a method of internal electrolysis was applied. The cell consisted of a silver anode contained in a Pt crucible serving as cathode. The plating solution contained sodium iodide-125 and sodium hydroxide. The yield of iodine-125 deposition for carrier-containing and carrier-free electrolyte solutions was determined. The deposition on uncutted Ag wires and on those cutted into 3 mm long bars was investigated. The influence of visible light on the coating process was examined. The leachability of iodine-125 from the silver wires as well as the activity distribution on the wires was measured. The obtained results indicate that the silver wire should be first coated with iodine-125 and then cutted into 3 mm long pieces. Based on this observation, a device for a batch-type procedure of manufacturing I-125 plated silver bars was designed and made. A design for simultaneous cutting and positioning of the activity-carrying bars into the titanium capsules is presented. This arrangement has been built and tested in trials. The tests confirmed that contamination of the source capsules can be minimized. Laser weldings of the titanium capsules were performed and the cross section of the welds examined by the use of an optical microscope.