Experimental measurements and Monte Carlo simulations of dose perturbation around a nonradioactive brachytherapy seed due to 6- and 18-MV photons.

Purpose: Radioactive seeds used in permanent prostate brachytherapy are composed of high-Z metals and may exceed 100 in a patient. If supplemental external beam treatment is administered afterward, the seeds may cause substantial dose perturbation, which is being investigated in this article.

Methods And Materials: Film measurements using 6-MV beam were primarily carried out using Kodak XV2 film layered above and below a nonradioactive iodine-125 ((125)I) seed.