New core configuration for producing Iodine 125 seeds

Abstract

Purpose: Cancer is one of the most complex public health problems. Prostate cancer is the second most common among men. In prostate brachytherapy use Iodine-125, which is fixated on a silver substrate, then inserted and sealed in a titanium capsule. This work proposes a new source configuration using epoxy resin substrate. Methods: Comparation and analysis methods were used to define the methodology for combining iodine-125 in polymers. The parameters were immersion time, reaction type, concentration of the adsorption solution, specific activity of the radioactive solution, need for carrier and chemical form of radioactive iodine. Results: The methodology developed with an epoxy resin was very good. The final radioactive intake on the resin was higher than 80%. The immobilization of the radioactive solution occurred in the matrix, without any loss or deposition of undesirable materials on its surface, as evidenced by the smear test. The material maintains its integrity when autoclaved at 140 °C. The curing process of the resin was 40 minutes. With the value of the initial activity of the Iodine solution by mass (774.2 lCi/g), it was possible to calculate the immobilization efficiency Average of 680 lCi/g. The immersion test in distilled water at room temperature did not exceed the limit allowed by ISO 9978, which is 5 nCi (185 Bq), proof of no leakage. In a computational simulation by the Monte Carlo Method, PENELOPE, the simulations were consistent with the values adopted by the literature for the GE Healthcare model 6711, which shows the value of the dose rate constant as 0, 965 cGy.U-1.h-1. Conclusion: The effective method for combining iodine-125 in epoxy resin was determinated. The major advantage was the high efficiency percentage fixation, around 82,1 3,2%, and the simplicity and safety of the process.