Studies on the production and quality assurance of miniature 125I radioactive sources suitable for treatment of ocular and prostate cancers

125I sources were prepared by adsorption of 125I on palladium-coated silver wires. The effect of reducing agent on percentage adsorption of 125I was studied and the amount of adsorbed activity on source core was studied by repeated adsorption cycles. The activity per source in the sources produced from the same batch varied with coefficient of variation (i.e. the ratio of standard deviation to mean multiplied by 100) less than 10%. The unencapsulated source exhibited low leachability (< 0.01%). The laser parameters were optimized to obtain quality welds with negligible leak rate. The sources were laser-encapsulated in titanium capsules of 0.8 mm (OD)×4.5 mm (l). The release of radioactivity from encapsulated sources in an immersion test at 50 °C for 5 h was <5 nCi (185 Bq). The surface contamination on the sealed capsules was found to be<0.05 nCi or 1.85 Bq per source. The sources were used in the treatment of a child having retinoblastoma.