Page 39 - PR 2014 2016 03 Applications of Ionizing Radiations

Applications of Ionizing Radiations | Progress Report 81

the following methods were developed: the unnecessary damage to healthy tissues or or-
seed core (silver) cutting, the titanium tube gans. For Iodine-125 stranded seeds, polyglactin
cutting, the iodine immobilization through its 910 (poly(lactic-co-glycolic acid)) (PLGA), with
deposition in silver substrate and the sealing of a coverage of polyglactin 370 (Vicryl ®) is used.
the seeds through welding process, so that the It was purposed, in this project, the study and
classification of the seeds, as sealed sources, and development of the synthesis methodology for
the leakage tests can be done according to the PLGA via ring-opening polymerization, as well
international norms. In the moment, the routine as its characterization, with the objective of
production line is settling up. The production using the synthesized material to manufacture
line consists in three gloves-boxes. In the first a material similar to RAPID Strand®. The results
one(,) the Iodine-125 will be adsorbed in the obtained show that it was possible to determine
silver core. In the second one, the titanium tube the optimal reaction parameters (time and tem-
will be sealed. And finally, in the third one, all perature) for PLGA in 80/20 (lactide/glycolide)
the assurance tests will be carried out. All the ratio. Using a temperature of 110° C and reac-
automation process of the welding glove and tion time of 24h, a yield of 86% was obtained,
the quality control glove are finished. and increasing the reaction time to 72 hours,
the yield was higher than 90%. The molecular
Methods for Iodine-125 mass values obtained from the samples are still
deposition in silver substrate very low compared to those obtained by other
authors in the literature (about 20%). Failures
Among the different ways to treat prostate can- in the sealing of vials, leaving them vulnerable
cer, brachytherapy with Iodine-125 seeds is an to moisture and oxygen, or lack of an efficient
option that provides good results and fewer side stirring system might be possible explanations
effects. In the present study, several methods for these results. A suitable chemical reactor
of deposition of radioactive iodine in a silver could solve the problem. Regarding polymer
substrate were compared in order to choose characterization, all techniques used not only
the most suitable alternative for the routine confirmed the expected structure of the poly-
production to be implemented at IPEN’s labora- mer, but also showed the highest proportion of
tory. The methodology used was chosen based lactide units compared to glycolide units.
on the available infrastructure and experience
of the researchers present. The better method Study and parameters survey for
will be implemented in the IPEN’s laboratory Iodine-125 source dosimetry to
for brachytherapy sources production. be applied in brachytherapy

Development of methodology for The objectives of this work are the develop-
the synthesis of Poly(Lactic Acid- ment and the study of dosimetric procedures
Co-Glycolic Acid) for use in the associates with the experimental acquisition
production of radioactive sources of the useful parameters for the Iodine-125
dosimetric characterization and to evaluate if
Iodine-125 seeds can be placed loose or strand- the developed procedures, in this work, have
ed in bioabsorbable polymers. Stranded seeds the basic conditions to determinate the do-
show some advantages, since they reduce the simetric analysis, that are fundamental for
rate of seed migration, an event that could af- clinical procedures. The dosimeters selected
fect the dosimetry of the prostate and cause for the analysis are the TLD-100 (LiF:Mg,Ti).