A surface mold using iridium-192 seeds.
A radioactive mold for treating skin was constructed by embedding ribbons of iridium-192 seeds in bolus material. The mold was designed to match the treatment area outlined on the patient's skin. Computer-assisted pre-planning was performed to optimize the seed strength, number of seeds, and spacing of ribbons. An outline of the treatment area was transferred to the surface of a uniform slab of tissue-equivalent bolus material 1.3 to 1.4 cm thick and planned locations for the ribbons were marked. Seeds were loaded into the bolus material at a depth to place the sources approximately 1.0 cm from the skin. The resulting mold was flexible enough to conform to the patient's skin and the seeds were so tightly confined within the bolus that there was no possibility of loss. Isodose distributions for the mold on a flat surface agreed well with preplans. A velcro strap and neck collar were used to attach the mold to the anterior portion of the patient's neck. For situations in which radioactive surface applicators are desirable, the use of iridium-192 seeds offers uniform dose within a highly individualized treatment area.
D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007495:Iridium / Q000627:therapeutic use*
D007495:Iridium