AUTORADIOGRAPHY FOR I-125 SEEDS

To study the interior design of model 6702 and 6711 iodine-125 seeds c ontact autoradiographs were performed using mammography film. Improved resolution was obtained using a pin-hole camera with a hole of 0.1 mm x 0.1 mm. With these techniques, qualitative determination of the rel ative activity distribution within each seed was possible. The number of the activated resin spheres and the positions of the centers of the se spheres can be exactly determined. A model calculation shows, that variations in the arrangement of the activated spheres within a seed h ave a moderate influence on the dose distribution at source distances below 10 mm. Knowing the exact source configuration may be useful when comparing dose calculations with measured data for model 6702 I-125 s eeds which are currently employed in ophthalmic plaque and implant the rapy of other tumors.