Physics and safety aspects of a coronary irradiation pilot study to inhibit restenosis using manually loaded 192Ir ribbons.

Radiation therapy has been successfully used in controlling some forms of benign tissue growth. A pilot study has been launched to evaluate the usefulness of localized radiation therapy in reducing restenosis after coronary angioplasty. In this randomized, double-blind study, patients with known restenosis received balloon angioplasty or additional stent implantation and were then randomized to receive either radiation or placebo treatment. Active sources consisted of 192Ir in the form of cylindrical seeds (0.3 x 0.05 cm). The seeds are embedded in a nylon ribbon. The nylon ribbon is passed through an indwelling coronary catheter. For this pilot trial, radioactive sources were exposed to blood elements and, therefore, required sterilization. A method of sterilization is described. A working team was developed to perform coronary radiation procedures at our institution. A description of the procedure is provided.